@qbngator: Themes are not available by default onT-Mobile G3s. I used a workaround posted by Gummyjelly on another post about themes. I couldn't figure out how to past the link here, so I'm attaching a screencap of the post that helped me out. You may have to try this a few times, because it didn't seem to work until I reinstalled the launcher a second time. Like Gummy says, you don't even have to keep the launcher installed. I uninstalled the launcher after getting the theme button working, and I can still use themes with the stock launcher.
T-Mobile G3