You have to use MPEG-2. DVD players don’t support playback of ProRes.
Export an FCP reference file of your timeline (File > Export > Quicktime Movie). No need to make the file self-contained if you are editing and encoding to MPEG on the same Mac.
Next, bring that file into Compressor and drop the “Best 90 minute DVD” settings onto your file. This should create 2 files in the end. An audio file (.ac3) and the video file.
You’ll want to adjust your settings in the inspector window. There’s too much there for me to explain. It’s be easier if you read the manual.

Robert J. Grauert, Jr.
http://www.robgrauert.com