Don't feel alone. GnomeToaster baffled me too. I recommend a different program: xcdroast. It comes with Fedora, so you can install it with System Settings > Add/Remove Applications. (Sound and Video category)
To get it to find the iso images, you have to click the Setup button on the main menu, HD settings tab, and add a directory. Save Configuration. Now at the main menu you can go to Create CD and Write Tracks. The image should appear in the right column. Burn it.
For more info, check out the FAQ