Depends on your isp and the protocol they use. If, for instance, you use pppoe [point-to-point protocol over the ethernet] like I do with Earthlink adsl, you could use rp-pppoe's setup script to get connected. You would have to know your user name and password and the domain name servers your isp uses (Mine has two: 207.69.188.186 & 207.69.188.185 [for illustrative purposes] and maybe a search domain; I use search.mindspring.com.
If you got this far and are still interested, see if rp-pppoe is installed:
$ rpm -q rp-pppoe
rp-pppoe-2.8-3mdk
If not, do # urpmi rp-pppoe and it will prompt you for the proper cd.
Then, as root, do # adsl-setup and you will be walked through a script where you put in your info.
This is just one way, the one I know