I am assuming it is an uncompressed avi file.
I would get 3 tools
1-Goldwave
2-TMPGEnc 2.5
3-DVD2AVI
First open the avi file in goldwave, you should be able to save the audio track as a .wav file, select save and save the audio track
Then open the .avi in DVD2AVI
File > Open>find your .avi > select ok>save project
select a destination and a name. it will be called "insert name here".d2v let it create the file
Open TMPGEnc 2.5, use the wizard
select DVD NTSC > next >video file: browse for your .d2v file > audio file: find the .wav file you created with goldwave > next > next > use the arrow buttons to make the file 95% of the DVD >next> select the destination you want and hit Ok
It will take a while, so I suggest you do this over night
To author to a DVD you will need a DVD authoring program, I would suggest TMPGEnc DVDAuthor 1.6 (TDA 1.6) It is easy to use and make a simple menu
You can find instructions
here for DVDAuthor.