I would assume that simply by being an IT major you would have some ground of knowledge. THen again depending on the school you go to, you may not. Where to start? First beat the living hell out of your english professor. Then from there... You have to pick the actual field of IT that you most want to work in. Even within security there are many. YOu like forensics, or maybe being just a network admin is your thing. You have to figure out where you want to start.

As for what to read... that question is about as hard to answer as anything. THere are plenty of books. Each with different skill sets and things they go over. If you just want to learn some basic stuff... Head over to amazon. THey have a wide range.

P.S. a personal favorite of mine is Security Warrior. But, I am an Orielly reader so anything by them is usually good to me.