How do you make particles come out of the back of the torso?

So, I was working on a script that makes particles come out of the torso when you double jump. I've tried and tried but still doesnt seem to work out. Ho would I make particles come out of my torso when I double jump ,press space twice, instead of turning me into a ball.

local player = game:GetService("Players").LocalPlayer
mouse = player:GetMouse()
local jump = false
local charging = false
local homing = false
local speed = 30
local direction = Vector3.new(0, 0, 1)
local lastPosition = Vector3.new(0, 0, 0)
local orginPosition = Vector3.new(0, 0, 0)
local lastTarget = nil
local velocity = Instance.new("BodyVelocity")
local spin = Instance.new("Part")
spin.Name = "Spin"
spin.Anchored = true
spin.CanCollide = false
spin.BackSurface = 0
spin.BottomSurface = 0
spin.FrontSurface = 0
spin.LeftSurface = 0
spin.RightSurface = 0
spin.TopSurface = 0
spin.Shape = 0
spin.Material = "Neon"
spin.Size = Vector3.new(4, 4, 4)
local hint = Instance.new("Hint")
hint.Text = "Spin Dash: Click and release | Homing attack: Double press spacebar"

function checkSit()
    if player.Character == nil then return true end
    if player.Character:FindFirstChild("Humanoid") == nil then return true end
    if player.Character.Humanoid.Sit == true then return true end
    return false
end

function transparent(value, object)
    if object == nil then return end
    object = object:children()
    if #object < 1 then return end
    for i = 1, #object do
        if object[i].className == "Part" and object[i].Name ~= "Spin" then object[i].Transparency = value else transparent(value, object[i]) end
    end
end

function onButton1Down()
    local torso = player.Character:FindFirstChild("Torso")
    if charging == true or torso == nil or homing == true or checkSit() == true then return end
    charging = true
    speed = 50
    spin.BrickColor = torso.BrickColor
    spin.Parent = player.Character
    for i = 1, 50 do
        if charging == false then return end
        if jump == true then break end
        speed = speed + 3
        spin.CFrame = CFrame.new(Vector3.new(0, 0, 0), direction) + torso.Position - Vector3.new(0, 1.01, 0)
        spin.CFrame = spin.CFrame * CFrame.fromEulerAnglesXYZ(-1 * i, 0, 0)
        if spin.Parent == nil then spin.Parent = player.Character end
        wait()
        if i == 1 then transparent(1, player.Character) end
    end
    if jump == true then transparent(1, player.Character) end
    onButton1Up()
end

function onButton1Up()
    local torso = player.Character:FindFirstChild("Torso")
    if torso == nil or jump == true or charging == false or checkSit() == true then return end
    charging = false
    lastPosition = torso.Position
    velocity.maxForce = Vector3.new(1e+005, 0, 1e+005)
    velocity.Parent = player.Character:FindFirstChild("Torso")
    for i = 1, speed do
        if jump == true or charging == true then break end
        if checkSit() == true then break end
        speed = speed - 1
        local trail = spin:clone()
        trail.Transparency = .8
        trail.TopSurface = 0
        trail.BottomSurface = 0
        trail.CFrame = spin.CFrame
        trail.Parent = player.Character
        game:service("Debris"):addItem(trail, .15)
        spin.CFrame = CFrame.new(Vector3.new(0, 0, 0), direction) + torso.Position - Vector3.new(0, 1.01, 0)
        spin.CFrame = spin.CFrame * CFrame.fromEulerAnglesXYZ(-1 * i, 0, 0)
        if spin.Parent == nil then spin.Parent = player.Character end
        velocity.velocity = direction * speed
        lastPosition = torso.Position
        if i == 1 then transparent(1, player.Character) end
        wait()
    end
    if jump == false or charging == false then
        velocity.Parent = nil
        spin.Parent = nil
        transparent(1, player.Character)
    end
end

function onKeyDown(key)
    key = key:lower()
    local torso = player.Character:FindFirstChild("Torso")
    if (key == " ") and jump == false and torso ~= nil then
        jump = true
        spin.BrickColor = torso.BrickColor
        for i = 1, 15 do
            if homing == true or jump == false then break end
            spin.CFrame = torso.CFrame * CFrame.fromEulerAnglesXYZ(-.5 * i, 0, 0)
            if spin.Parent == nil then spin.Parent = player.Character end
            wait()
            if i == 1 then transparent(1, player.Character) end
        end
        if homing == false then spin.Parent = nil transparent(1, player.Character) end
        jump = false
    elseif (key == " ") and homing == false and torso ~= nil then
        homing = true
        jump = false
        transparent(1, player.Character)
        local target = nil
        local distance = 100
        local list = game.Workspace:children()
        for i = 1, #list do
            if list[i].className == "Part" and list[i].Size.magnitude < 6 and list[i] ~= lastTarget and (list[i].Position - torso.Position).magnitude < distance and list[i].Position.y < torso.Position.y then
                target = list[i]
                distance = (list[i].Position - torso.Position).magnitude
            end
        end
        if target ~= nil then
            lastTarget = target
            velocity.maxForce = Vector3.new(1e+005, 1e+005, 1e+005)
            velocity.Parent = torso
            transparent(1, player.Character)
            for i = 1, 50 do
                if jump == true or (torso.Position - target.Position).magnitude < 4 then break end
                spin.CFrame = torso.CFrame * CFrame.fromEulerAnglesXYZ(-1 * i, 0, 0)
                if spin.Parent == nil then spin.Parent = player.Character end
                local trail = spin:clone()
                trail.Transparency = .9
                trail.TopSurface = 0
                trail.BottomSurface = 0
                trail.CFrame = spin.CFrame
                trail.Parent = player.Character
                game:service("Debris"):addItem(trail, .5)
                velocity.velocity = (target.Position - torso.Position).unit * 200
                wait()
            end
            spin.Parent = nil
            transparent(1, player.Character)
            homing = false
            velocity.maxForce = Vector3.new(0, 1e+005, 0)
            velocity.velocity = Vector3.new(0, 50, 0)
            wait(.2)
            velocity.Parent = nil
        else
            originPosition = torso.Position
            lastTarget = nil
            velocity.maxForce = Vector3.new(1e+005, 1e+005, 1e+005)
            velocity.Parent = torso
            for i = 1, 20 do
                if (torso.Position - originPosition).magnitude > 20 or checkSit() == true then break end
                spin.CFrame = torso.CFrame * CFrame.fromEulerAnglesXYZ(-1 * i, 0, 0)
                if spin.Parent == nil then spin.Parent = player.Character end
                local trail = spin:clone()
                trail.Transparency = .9
                trail.TopSurface = 0
                trail.BottomSurface = 0
                trail.CFrame = spin.CFrame
                trail.Parent = player.Character
                game:service("Debris"):addItem(trail, 1)
                velocity.velocity = torso.CFrame.lookVector * 180
                wait()
            end
            velocity.Parent = nil
            spin.Parent = nil
            transparent(1, player.Character)
            wait(.25)
            homing = false
        end
    end
end


    if mouse == nil then return end
    if player:FindFirstChild("Message") ~= nil then player.Message.Parent = nil end
    hint.Parent = player
    mouse.Button1Down:connect(onButton1Down)
    mouse.Button1Up:connect(onButton1Up)
    mouse.KeyDown:connect(onKeyDown)
    mouse.Move:connect(function()
        if player.Character:FindFirstChild("Torso") ~= nil then
            direction = (mouse.Hit.p - player.Character:FindFirstChild("Torso").Position).unit
            direction = Vector3.new(direction.x, 0, direction.z)
        end
end)

I want particles instead of the part (Ball)