Most of the complexity in learning to make DVDs is in the video encoding. There are fairly standard settings that you'll usually use for audio, so you don't have to make many decisions. Since you'll need some information about your audio when you're encoding video later, it's easiest to prepare your audio assets first.
This is the third guide for the Basic DVD Authoring Project. If you're not familiar with the project you may want to start with the first guide. If you're just trying to learn about the audio formats used on DVD this can be useful on its own. If you're just beginning with digital video you may want to read our Digital Video Basics guides first.
Haali Media Splitter
TMPGEnc AC-3 Plugin
Basic DVD Authoring Project guides: