What you need to do is once you have put the new roms into the roms folder boot up MAMEox again and when you are on the main screen press your start button and a small box will appear,scroll down until you see scan for new roms.
hit the A button and hopefully after it has updated your should see them in the games list.
Im using Mameox ver.65b::VC7 Uses MAME ver 0,69 if i press my black button at the top of the screen where it says names clone and no clone apear..but i dont know how to scan, if a press the A button the game at the top of the list starts.....I know it must be somert simple ,but can I find it NO!!! LOL!!!!!!