Ah-huh to everyone's posting up to now, I'd like to suggest looking for a training guide on the web (I've seen some of em, though don't have them book-marked). Or check out Bicycing magazine which usually has info on training, and lately has been offering (on-line version) an on-line coach to work with you for a fairly inexpensive figure. Scroll down to the bottom of the on-line home page and it should be in a 2x2 inch click on box...

I have to admit that working out slowly for longer time gets me that "I just worked out" feeling, so the suggestion to go slow over longer time is good one.

Doing intervals also is a good thing too - sprint for 1 minute, slow down for two or three, and sprint again. This also helps build different things...

good luck!