I'd really suggest doing some reading. Even if you don't want to do the programs, you need to get a more solid grounding in how the whole process works. Here are a few places to start:
Body for Life by Bill Phillips
Body for Life for Women by Dr. Pamela Peeke
The BodySculpting Bible
Exercise Anatomy
Your Body Revival by Dave Draper
If you go to the top of this forum, there are some stickies with basic information and a few websites listed.
www.stuptuous.com is a great source of info- which I always spell wrong, so go look at the stickies
If you can't bench your warmup weight- it's too heavy for a warmup
Sorry to be so brief- gotta go to work!
Mel