You can customize the background, fonts and text colors right in the Premiere Elements's Movie Menu Adjustments workspace. Is that what you're talking about?
To truly customize a menu or modify a template file, you'll need to open a template in Photoshop or Photoshop Elements. In version 11, this is an especially challenging manuever, since the templates only download to your computer as you select and apply them -- and there are some special things you need to do that you didn't have to do in previous versions. It's not for the feint of heart.
But I do give detailed instructions for doing so in my Photoshop Elements/Premiere Elements 11 combined book.
I've also created a 2-part tutorial describing how to do it for subscribers at http://Muvipix.com.
The "menus" in the tools drop down was not accessable for whatever reason. After closing and a reboot, it appeared. Thanks for the help again! One other thing, is it possible to add more text to the main menu, other than what is already there. eg: Add a personal message to viewers....
As Steve points out, that is possible from the Menu design Panel. One exception, that can be very important, is that most Menu Set Templates have a Text Object, that can be easily altered. That Text is but a graphic on the Menu. Buttons, howerer, are a slightly different matter. If one changes the Text in a Button (will be part of that Button's Layer Set), adding more Text can create a problem. By the DVD-specs., Buttons cannot overlap, even by 1 pixel, so if one adds Text to a Button, and makes it large enough to overlap any other Button, the Menu will not function.