How do I connect this computer to the internet?

I am running a PC on Windows XP and recently reformated it. I never have had any problems with this PC when I format it before and now suddenly it won’t connect to the internet. Anyone here want to take a shot at trying to get this one back up?

This computer is connected through a network and there are three computers total on it. Two of the computers connect, but my recently reformat PC will not. The PC is running at this moment and shows that it thinks it is connected but it is not, the wire is out of the back.