Please help!

I have a simply page that contains an iframe, and the page located inside this has a series of check boxes. Upon hitting submit, javascript checks which options are selected and builds up a new url from there. What I'm struggling with is how to get this page launched inside the iframe.

From the home page I can get the page inside the iframe changed; I'm simply struggling when dealing with a page loaded inside the iframe. I've tried targeting the iframe, but it doesn't seem to work in the same way that frames do.

Where am I going wrong? Thanks.

Clive.