If you want a data dvd with mp3's on it, just drag, drop, and burn as data, not DVD.
If you want a dvd audio disk, you'll need to transcode all your mp3's to AC3 (or mp2), using Ffmpeggui, or Besweet/Belight, then author as audiodvd in DVDLab Pro.
There are a couple of other pay programs that will create an audio dvd, but I don't know if they have demo downloads. At least dvdlab has a fully functional 30 days.
You can fit about 450 songs on a dvdr in AC3 format.