I highly recommend checking out a book called Starting Strength by Mark Rippetoe (there is a separate DVD as well). This book, by far, has the best descriptions and instructions of how to properly perform barbell exercises as well as one of the best basic strength training programs.

There are endless number of exercises you can do with a barbell but I would stick to the basics like:

Squats (although since you don't have a squat rack, it won't be easy)
Deadlifts
Overhead Presses
Bench Press

Thank you, KDuffer

Quick update -

I just printed out the exercises from the links Penguin gave and I'll start incorportating them into my routine this week. I'll let ya'll know how it goes. Thanks again everyone