Once you've got X up and running, you can start running graphical clients like browsers, games and so on. Specifically, you'll probably want to start at least one terminal emulator (xterm, gnome-terminal, etc.) for command line work. These graphical clients can generally be started either by typing their name in a terminal session, or by following the menu system. Either way should work fine.
If you're running the GNOME desktop under RedHat, the xterm icon on the default bottom panel is annoyingly next to the similar logout icon. Or maybe that's just me.