Navigation Menu in theme Twentyten

I’ve attempted to create a navigation menu in the theme Twentyten. I followed the instructions in Codex under Navigation Menus and placed the code in the theme’s functions.php file. I placed all the required coding at the end of the file which might have caused the problem. The directions do not specify where to put the code. I received an error message after uploading the changes. Can anyone tell me how to use the navigation menu in the Twentyten theme?

John