how do i get all the player in game not just local player?

I'm not sure what you mean by "not just local player" as server scripts cannot get the local player but to get the player that is hit, first create a on touched event:

script.Parent.Equipped:Connect(function()
    equipped = true
    char = script.Parent.Parent
    humanoid = char:FindFirstChild("Humanoid")
end)

script.Parent.Unequipped:Connect(function()
    equipped = false
    char = nil
    humanoid = nil
end)

script.Parent.Handle.Touched:Connect(function(hit)
    if hit and equipped and char and humanoid and humanoid.Health > 0 then
        local targetHum = hit.Parent:FindFirstChild("Humanoid")
        if targetHum then

        end
    end
 end)

this checks if the tool is equipped, if the player character exists, and if the humanoid exists then checks if it hit something w/ a humanoid like a zombie or a player then:

local dmg  = 15

script.Parent.Equipped:Connect(function()
    equipped = true
    char = script.Parent.Parent
    humanoid = char:FindFirstChild("Humanoid")
end)

script.Parent.Unequipped:Connect(function()
    equipped = false
    char = nil
    humanoid = nil
end)

script.Parent.Handle.Touched:Connect(function(hit)
    if hit and equipped and char and humanoid and humanoid.Health > 0 then
        local targetHum = hit.Parent:FindFirstChild("Humanoid")
        if targetHum then
            local HitChar = targetHum.Parent
            targetHum:TakeDamage(dmg)
            if HitChar then
                for _,v in pairs(HitChar:GetChildren())
                    if v:IsA("BasePart") then
                        v.Color = Color3.fromRGB(9, 137, 207)
                    end
                end
            end
        end
    end
 end)

so this also damages the humanoid that was hit and cycles through all parts of the character that was hit and if it is a base part, (mesh part, truss part, corner wedge, etc.), then changes the color of it to blue.