While they may be a little confusing at first, there are many how-to's floating around the net. I think the best way to learn the stuff is by doing it. It takes a lot of research, but along the way you pick up stuff you weren't looking for, and begin to get a nicer picture of what is going on. Check out www.linux.org
at the documentation section... there's how-to's galore there. Also, a lot of the applications have tutorials that are great.
I have a great link to a network administrator online book, but it's on my other system, and i can't seem to find it now. I'll get back when i boot that system up again.