How do put a 16x9 picture on my menu as a background?
I made a snapshot of the video which is 16x9, but when I place
it as background picture it changes to 4x3.
The project properties are set at 720x480.
Thanks in advance to all of you helpful folks out there.

720x480 is 4:3.

You need to create a widescreen DVD project if you wan things to be 16:9.

My DVD project was rendered as DVD widescreen in Vegas Pro 8.
After printing to a DVD it plays as a 16x9 video except that the Menu
is 4x3.
I'm confused.

You need to set the project type in DVDA as Widescreen DVD.

Where do I change settings and what settings do I use?

File -> Properties -> Video Format

Click on the pulldown on the right.

Select "NTSC Widescreen 720x480"

Click "Apply"

Click "OK"

Automagically you have a 16:9 project.

In the future, when making a new project, you can do this:

File -> New

Under Project Video Format, select "NTSC Widescreen 720x480" and automagically, you have a 16:9 project.

I just tried it, and it worked.
I thought I did this, but I guess I didn't click apply.
Thank you for your help.