It's as simple as creating a style sheet, targeting items you don't want to print, or create a class such as .noprint, and hide the items with { display: none; }

You'd want to put that CSS in a separate file and include it like this:

<link rel="stylesheet" type="text/css" media="print" href="print.css" />

The important bit is the media="print". Look at mine all you like, nice of you to consider asking :)