I'm a complete beginner, but I know what I as an end user would like. I'm trying to use catalyst like a frame. I want people to be able to click on a button on the side and have a page open up within a pre-defined rectangle on the page. What I don't want is to navigate away from the page to the new url. Is this possible without flex builder? Is this possible at all? Thanks.
There's no way to create that behavior directly in Catalyst. However, you can do it with a little HTML hacking. You'll want to use the IFRAME tag: http://www.w3schools.com/TAGS/tag_iframe.asp
When you publish your project as a SWF, one of the files that is created is an HTML file that wraps your SWF (it's typically called Main.html). You'll want to edit that file.