Google CCNA. You'll have to sift through a lot of junk, but there are some quality sites out there that i found when i was deciding what i wanted to study. As i would advise you to take an "introduction to computing" class from a local college. These courses are generally very slow paced and easy to understand, and can normally be taken online. The reason i suggest this is so that you can get a better idea of what you'd like to do from an IT standpoint. Network in and of itself purely has to do with getting data from point A to point B. The fact that your school uses PC's (with their own processors) as opposed to thin clients or terminals (take their power from the server) is much more a Systems admin topic.
If you'd like a "little" info, the biggest reason for the multiple PC's is cost. Having a single server run 50-60 thin-clints is very expensive when you consider how much that server would cost, and how much thin-clients cost. The average "corporate pc" can be had for around $300.00 each. Thin client range from 200-100, so you're not saving a lot of money going with thin client. You factor in the added cost of the server, and you'll normally break almost even. The 2nd part of the equation is fault tollerance (the ability of your network to continue working even with problems). Should a single PC fail in your schools current setup none of the other PC's on the system will be negatively affected. On the contrary, if you school used thin client and the server were to fail, all workstations would cease to work.
hope that sort of gives you an idea