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)