The best way to contact other users are the forums. To get a more extensive help you can also Get Support with other resources.

The available forums are:

AdvanceMAME Help for the AdvanceMAME and AdvanceMESS emulators (advmame/advmess).
AdvanceMENU Help for the AdvanceMENU frontend (advmenu).
AdvanceCOMP Help for the AdvanceCOMP recompression utilities (advpng/advmng/advdef).
AdvanceSCAN Help for the AdvanceSCAN roms manager (advscan).

All the forums accept anonymous posts and allow anonymous search of the archives. If you register a SourceForge account you can also be notified of new messages.