Yo Dan the Man:
I'm sure many of the troops out there can give you BUNCHES OF information about a sequencer; I will just give you a basic example because that's all I know.
If you have a synthesizer with a sequencer, the sequencer amounts to an electronic tape recorder, only NO TAPE. Thus, if it is an 8 track sequencer, you can put down 8 different parts to a song; you create the parts like keys, chords, strings, drums, solo horn, etc. Then, the sequencer plays them all back and you mix it down to something like tape or minidisc or whatever.
I have
a Yamaha DX-7 synthesizer - a great old box; it does not have a sequencer; so, I play the chords into my MD-8 mini-=disc recorder, then, I over-dub 4 or 5 more tracks like bass, strings, drums,[always get the drums down first then everything else is easier] and perhaps I leave a track or two for a vocal. Of course you can do the same things with a PC and a sound card program or an Adat or whatever your imagination and learning curve is attracted to.
Recording is not prescriptive, I recently read. It is a creative process each time you do it.
So, man, get out there and do it.
Green Hornet