If you a new to bicycle repair, it has gotten a bit more complicated over the years. But there is no reason that with the proper tools and resources you can't learn over time to fix your own bike.
Having said this, if you are used to staying upright on a bike, pay a professional mechanic to adjust your do-it-yourself fixie's chain line for the first time. Then, read, ask, watch, copy, practice the right way to do things.
Good professional bicycle mechanics perform repairs and services faster, more accurately, and more thoroughly than hobbyists.
This Park tool site coupled with some words of wisdom and practical experience from Sheldon Brown is a good place to start.
Remember, bicycle repair is not rocket science; consequently, bike parts are not as strong as rocket parts. So refrain from dropping expensive alloy components on the cement floor in your garage.
http://www.parktool.com/repair/byregion.asp
http://www.sheldonbrown.com/articles.html
