Try Kinternet, kppp, and whatever Gnome uses
Like aaa says, the pppd (the ppp daemon) comes with Redhat and by running one of the previously mentioned programs, it should load up automagically which is a good thing
You will have to do some configuring, which amounts to telling kinternet (or the others) your:
Connection, e.g. Earthlink
Your user name, e.g. firstname.lastname@example.org
The phone number
Password is optional, can be added during dialup phase
And that's about it (off of the top of my head)
Click once on the icon, or call it up from the menu, add password (if you didn't make that part of the config) and wait a moment. Helps to have the log file showing so that you can see what's up.
Fire up Mozilla, surf.