Leesa,
Just burn a dvd from Studio9. I can help you with the exact settings when I get home, but here's basically what you do, now that you have the .avi file.
Open a new project. Pull in your .avi file. Add whatever dvd menu you want at the beginning, copyright info, that sort of stuff.
Then, under "make movie", select "dvd" and have Studio 9 burn it to the dvd. This way it will play in dvd players easily, and people without a computer can play it.
No need to mess around with nero etc., although those are good programs. Studio 9 will get it done for you.
A hint though: The way you did it, making an .avi first, then starting a new project, pulling that avi file in, and burning to dvd, is the best way (otherwise you can end up with your sound out of sync if you try to go directly to dvd from the original project).
Send me a pm if the settings for mpeg aren't clear and I'll check it when I get home - I think you want mpeg2, but I think there is a setting that is called "DVD Compatible" or something like that. That one has always worked well for me.
If the avi file is 3g, the mpeg file will be smaller - mpeg is a compressed format. You should be fine, like someone said, a dvd can hold 4.7g. But it does require a bit of processing - your computer will crunch it for awhile, maybe like 15 minutes or something? I can't remember exactly.
Nero etc is good, but you don't need it, you should be fine with Studio.
And while you're at it, burn a data dvd of your avi file to save for the future.
Susan