If you have red hat 9, and want to burn a CD, just put the blank CD in the drive. If things are set up right, and you're using GNOME, nautilus should open with a "Burn CD" button on the toolbar. Just drop the files and directories you'd like to burn in, then hit "Burn CD".
Nothing to it
If your burning needs are more advanced then yeah, you might need a separate program...... if you can't figure out eroaster then just use something else, the world is flooded with linux cd burners