Click on either Shirts, Pants, or T-Shirts in the left column, depending on your design. Click the gear to the right of the item you want to sell. Click Configure, then select Sales. On the Sales page, click to turn on the "Item for Sale" option.
Open the image in your chosen editing software such as Photoshop, GIMP, or MS Paint. ...
Each part needs to be a specific size; Large square, 128 × 128 pixels. This part goes on the front and back of your torso. ...
Apply your design to each part, save it, and you are done!
How to Sell Roblox Created Items
Right now only an account with a membership can participate in private selling. Additionally, as with trading, only items marked as Limited or Limited U are able to be sold. If an item is Limited or Limited U, there will be an icon declaring it as such underneath the item's picture when viewing its details page or when browsing the catalog.
How to Create and Sell Your Own Items
If you would like to create pants, a shirt or a t-shirt from scratch, you can sell those as well. For steps on how to create and sell items, check out the Developer Hub for more information.