i bought one off ebay a couple a days ago, i was wondering if it is a hard install. is there any sites were i can find a installation for a bmw?

You probably should have thought about that before you bought it dont you think? Is it hard, depends, how much have you worked around automotive electronics? Your car should be prepped for alarm, if you have the bentley manual, alarm manual, you should be ok. If you dont have the bentley, go to a decent car audio/security place in your town and ask if they can give you a printout for your car. They can print you out a paper that will tell you what you need to do, and where the wires are and the colors.

Good luck