1. Before you can create a shirt in ROBLOX, you must have a subscription. What this means is that you must have already subscribed to their premium plan. However, if you don't have an existing subscription, just navigate to https://www.roblox.com/premium/membership?ctx=preroll.
2. Navigate to https://static.rbxcdn.com/images/Template-Shirts-R15_07262019.png to open the Roblox shirt template page.
3. Once you are able to open it, right-click on the shirt template to save it directly to your computer.
4. Install a photo-editing software and open it.
5. Use the software to open the shirt template you saved in step 3.
6. Edit and save the shirt template.
7. Use any browser on your desktop to navigate to https://www.roblox.com/games.
8. Check the upper left area of the page and click on the "create" tab, then click continue.
9. Check the bottom of My Creations" and click "Shirts" then click browse.
10. Upload the photo you edited in step 6.