If you dont know any music theory, like how to read rhythms on notation, then I suggest you start there, by getting a good theory book/cd that teaches how to read time signatures, and how to do different rhythms using different notes, learning how to count using the different variations of kinds of notes.
If you know all the different kinds of notes (8ths, 16ths, halfs, wholes, dotted halfs etc.....) then you should be able to lay out drum ideas that you have in your head, straight to your midi sequencer.
Then you can move on to getting books/cds on different styles of drum patterns for drummers......for more complex drum lines.
Bass lines, is the same concept. Whatever song it is your playing, you have to know some theory like what key the song or measure is in. Then you have to figure out where the
chord progressions are going. Then you can go ahead and tackle trying to lay out some bass lines. There are many books/cds on how to play great bass and stuff like that...for different styles. Once you know basic theory, you can apply it to any instrument when you are writing music.
