I've started trying to arrange songs like whole songs for a 5 piece band but i cant seem to write a lead, rhythm, and vocal line that all go together...i can write each individual but not combinded...how is it done

I guess at this point i am just looking for some general advice and tips and open discussion.

Quote by j.pagejr.
Start with a rhythm and build off it.

That's exactly it. Start off with the rhythm section. You can't make a lead part if there's nothing for it to follow or accompany. Vocals as well come later on.
^ actually thats not entirely true. i have written leads and then put rhythms behind it. i say just take a part, whichever part you write first and make a quick cheap recording of it. (invest $30 in a crappy tape recorder if nothing else) then go over it with the other instruments (pc recording works way better for this but if you have a decent memory then a tape recorder will work) once you have a rough idea of the song it might help to hum out a melody that you could hear yourself or someone else singing.