Major Macbook Internet Problem

Ok so I have a Macbook just about one year old and I have used a wireless Airport connection on it up until now. I'm in college so now I need to plug into their network using an ethernet plug.

I tried using the ethernet plug and it just hasn't been working. I have seeked out help and the jist I have gotten from people is that the computer is not detecting the ethernet plug connection. I have followed all the steps right I believe to check the connection and it just doesn't seem to detect it.

I have tried other ethernet plugs and other macbook users haven't had a problem. I fear it could be a costly hardware issue, but I'm still not sure.

Can anyone help me with this? This is my last resort before I go to a professional to get it fixed. Can someone tell me the steps I should goto to check the computer so I can tell if it is truly a hardware problem? Also, could it be I need a certain ethernet plug for this MAC that me and others just don't have?

Thanks.