This is what the socket looks like click here it sometimes has the 3 monitor symbol by it. You can also check Device Manager to see if you have any network connections on your PC, right click on My Computer, select Properties then Device Manager, then click on Hardware tab, look for any mention of network adapters.
If your PC is 5 years old it's possible that it may not have one. In that case you will have to check if you have a free PCI slot in your PC click here and if you do you will need to buy and install a network/ethernet card. Don't worry it's very easy to do.