I have a roland XP 30 and i am intrested in making RAP BEATS i have every thing worked out i use cubasis to make the music.
The problem is how can i make the bass and the drum sounds good do i have to play the drums like i play the melody or do i just make it and let it do it itselfe. whats the best way to do it please HELP!!

I would recommend you use the xp-30 to make the music and cubasis to SEQUENCE the beats. You can do either of your suggestions for recording beats. 1. Play and record your beats as you do the melody on a MIDI track, or 2. Write the MIDI notes in by hand within Cubasis.

And please, from now on, read your manuals and you'll find answers to these kind of getting started questions a lot quicker than waiting for some sap like me to answer them. Unless you don't have the Cubasis manual... but of course you do!