Getting Started

To get things started, you'll need to insert either a Script or a LocalScript into StarterCharacterScripts.

• With a normal Script, players can see other players' trails.
  

• With a LocalScript, players cannot see other players' trails. Just their own.
  

Once you've done that, open up the script, and delete the print("Hello world!") line.

Creating the Trail and it's Attachments

In order to give the player a trail, we'll need to create one for them. And to create objects, we'd have to use Instance.new(). Type this in the script:

local trail = Instance.new("Trail")

Every trail needs two unique attachments, so we'll have to create those too.

local trail = Instance.new("Trail")
local att0 = Instance.new("Attachment")
local att1 = Instance.new("Attachment")

Now we've created the trail and it's attachments for the player, but there are also properties that we must set.

Changing the Properties

We put the script in StarterCharacterScripts for a good reason. The script will be inside the player's character, where the HumanoidRootPart is, which is what will parent the trail and attachments.

local trail = Instance.new("Trail")
local att0 = Instance.new("Attachment")
local att1 = Instance.new("Attachment")

trail.Parent = script.Parent.HumanoidRootPart
att0.Parent = script.Parent.HumanoidRootPart
att1.Parent = script.Parent.HumanoidRootPart

Now we're going to set the trail's attachments. As said above, trails must have two unique attachments.

local trail = Instance.new("Trail")
local att0 = Instance.new("Attachment")
local att1 = Instance.new("Attachment")

trail.Parent = script.Parent.HumanoidRootPart
att0.Parent = script.Parent.HumanoidRootPart
att1.Parent = script.Parent.HumanoidRootPart
trail.Attachment0 = att0
trail.Attachment1 = att1

Trails are enabled by default, but there's nothing stopping you from setting Enabled to true.

local trail = Instance.new("Trail")
local att0 = Instance.new("Attachment")
local att1 = Instance.new("Attachment")

trail.Parent = script.Parent.HumanoidRootPart
att0.Parent = script.Parent.HumanoidRootPart
att1.Parent = script.Parent.HumanoidRootPart
trail.Attachment0 = att0
trail.Attachment1 = att1
trail.Enabled = true

We'll now adjust the two attachments' position to spread them out.

local trail = Instance.new("Trail")
local att0 = Instance.new("Attachment")
local att1 = Instance.new("Attachment")

trail.Parent = script.Parent.HumanoidRootPart
att0.Parent = script.Parent.HumanoidRootPart
att1.Parent = script.Parent.HumanoidRootPart
trail.Attachment0 = att0
trail.Attachment1 = att1
trail.Enabled = true
att0.Position = Vector3.new(.5, 0, 0)
att1.Position = Vector3.new(-.5, 0, 0)

After that, you can freely set the Lifetime of the trail, MinLength, MaxLength, and basically any other property.

Now test the game. If you did everything correctly, you should have a trail that follows you around.

Final Script

--Remember, this must be in StarterCharacterScripts
local trail = Instance.new("Trail")
local att0 = Instance.new("Attachment")
local att1 = Instance.new("Attachment")

--Feel free to change other properties
trail.Parent = script.Parent.HumanoidRootPart
att0.Parent = script.Parent.HumanoidRootPart
att1.Parent = script.Parent.HumanoidRootPart
trail.Attachment0 = att0
trail.Attachment1 = att1
trail.Enabled = true
att0.Position = Vector3.new(.5, 0, 0)
att1.Position = Vector3.new(-.5, 0, 0)