Selling book?

I just finished my first book and sent the manuscript to my publisher. I'm still not very positive about how my work gets distributed to the public. I know he told me that 90% of getting it marketed would be my responsibility. Fine. And he would set up Internet sites so future readers can download the book. Okay. But, what about paper sales? How do you go about getting the distributed throughout the nation. Do you contract a warehouse? If I order, say 50 paper backs and 30 hard covers, do I pay for that? I'm sure I'll learn quickly, hopefully before my money runs out. LOL. Would like some feedback and some suggestions. Thanx.