Create or log in to a Roblox account
Get Roblox Premium if you want to upload clothing
Open a image editor like Photoshop, GIMP, or Photopea
Download the official Roblox shirt template
Design your shirt on the template
Save the file as a PNG
Go to the Roblox Create page
Open the Clothing section
Select Shirts
Click Upload Asset
Choose your PNG file
Enter a name for the shirt
Pay the upload fee if required
Submit the shirt for approval
Wait for Roblox to review it
Wear or sell the shirt after it is approved