MAME4droid is an Android emulator. iMAME4all is used to run games supported by the original MAME 0.37b5, but it is also capable of running games from newer MAME versions. 

To run a game, use the "Run" option. You can also use the "Search" option to search the original games for your phone, using the title of the game and the description. 

If you are using MAME4droid for Android, you will also need to place your MAME-titled zipped ROMs in the appropriate folder. To do that, use the "ROMs" option.