How to make a custom roblox theme or something

STEP 1
Go here: https://chrome.google.com/webstore/detail/roblox-themes-beta/bhnkonnaaipkhoaiakbcpcaolflgmnhl

If not then cant help u.

STEP 2
Install it

STEP 3
GO 2 THAT EXTENSION AND CREATE A NEW 1 AND CHOOSE COLOuRS, THEN GO 2 ROBLOX THEN REFRESH THEN BOOM DONE.