Bicycle Mechanics - want to learn to fix bikes

I know very little about bicycle mechanics and repair. This past week I picked up three bikes that someone had put out for trash pickup. They are cheap bikes, nothing fancy. Each has something wrong with it: messed up spokes, no brakes, wheel out of whack, pedals falling off, etc...
But now I officially have bikes I can screw around with. I'm 16 and before I just had my one bike. So the question- what can I do with these bikes that'll teach me everything (or at least a lot) about the makeup of bikes and how to maintain/repair them. Should I try to disassemble them, etc. I'm a definite newbie.
Any advice appreciated.

go to town with them.

Take them all the way apart then put them back together again.

Yea, take em apart. Cheaper bikes generally don't need those fancy special tools so anything would work and It would definitely help. Once you get your orientation on the ways things are on a bike, it'll be pretty simple and all those little differences will be easy to adjust to and won't look foreign to you. The first bike I've ever done anything to was a Wal-mart Magna and now I can build bikes. :)

Try to take the best parts and build yourself a working bike out of those 3 without spending any money - that will be a good challenge.

To work on bikes, you basically just need a basic understanding of how bearing work and how to use about half a dozen specific tools.

I got a $49 set of bike tools from Performance, and a year later I built my first fixed gear from the frame up.

As you are taking apart, take notes, take your time and study the parts and where they come from. Since there are not that many parts it is not like some complicated machine. As z415 said,,,get one good bike from the three, if you can and make it good...........as you are putting things together remember to use grease or oil on those areas that need it... and use the resources. peace