Open Roblox and sign in
Go to the Create page
Select your experience or open the Avatar Shop creator tools
Prepare a T-shirt image as a square or rectangular design
Make sure the image follows Roblox upload rules
Save the image file on your device
Go to the Roblox Creator Dashboard
Select the item type for a T-shirt or shirt
Upload the image file
Enter a name for the item
Pay the required upload fee if needed
Submit the item for moderation
Wait for approval
After approval, equip or sell the T-shirt in Roblox