I'm not much of a network guy, but you should be able to access all files by clicking the start button(assuming you have Windows), Then click network connections to your right, and in there should be folders of some sort you can click on. If you have no network connections, there is a setting in the control panel I'll tell you about that can manually allow file sharing. Do you have the wireless network already set up?
And for the second question, I don't know a whole lot about severs either, but most people use them for hosting large internet websites, connecting more then 8 computers together, They can be used for all kinds of things.