Hi Manoneeta,
to develop a multiplayer games using GASP, firstly Java must be a well known language for you, then you can try the getting started demonstration games (available in downloads section).
GASP has been created to help developers to support mobile multiplayer games and more generally multiplayer games, we have tried to make it accessible for new developers.
But as for all new software, there is a time to learn our middleware and to manipulate it in a right way.
I think you should try it and ask us if you have any question about GASP.
Best regards,
Romain Pellerin