Wecome to CD Freaks forums! Hope you will enjoy your stay here!
You'll see that there is allot of info in our database. You can access this database by hitting the searchbutton in the righttop of your window. If you would, for example type convert avi to mpeg2 (DVD = mpeg2) here you will see allot of topics of other people who asked this question in the past. Very handy I must say.
You might also want to have a look at Chickenman's tutorial where he explains how you can convert your DivX/Xvid movie (which your avi probably is) to a mpeg2 file which you can play in your standalone DVD player.