To get Internet on Linux you need the following :
an ip-adress on your NIC (eth0). You can check this with ifconfig.
Consider an adress starting with 169 a wrong adress.
If you get your ip from a dhcp server, you should get one.
You need DNS servers, you can find the entries in /etc/resolv.conf
It should look like this :
for example, you will have your own dns servers probably.
Then, if you use a router or gateway at your home, you must tell your pc so. You can do this with : route add default gw 192.168.0.1 (the ip of your gateway can differ from what i type here)
If you could post a little more info about your network it would be helpfull. Hope this post was a help for you however.
Good Luck !