To create a particle emitter you would just change your line on the creation to:
local Effect = Instance.new("ParticleEmitter")
There is also no “Feet” body part so for R15 you would either need to use RightFoot and/or LeftFoot or for R6 “Right Leg” and/or “Left Leg”.
Then it is just a matter of setting the values to the correct types they expect as the “Color” property expects a ColorSequence and some of the other properties actually expect a NumberRange so you must use those to set the values. You would also want to Destroy the Emitter in the InputEnded event otherwise you will have quite a few emitters in the character.
Why create it each time you need it?
You can just use this setup to load it into the player with a script in the Starter Player Script service and make it Enabled = false.
Then when they run you just enable it and disable it when they stop running without Destroying it.
Also, remember that it’s ParticleEmitter, not ParticalEmitter.
As I already stated, you just need a Local script inside your StarterPlayerScripts | Documentation - Roblox Creator Hub that will create, format and place the ParticleEmitter into the Player. That way when the player loads into the game or respawns the Emitter is already loaded into their avatar and you can just Enable it true or false.
local player = game.Players.LocalPlayer
local character = player.Character
local function connectCharacter(character)
local emitter = Instance.new("ParticleEmitter")
-- Apply settings
emitter.Parent = character:WaitForChild("HumanoidRootPart")
end
player.CharacterAdded:Connect(connectCharacter)
if character then
connectCharacter(character)
end