Category opens in a pop up

When a user clicks on a category, I'd like it to open a pop up window.

Is this possible?

It could be done. You'd need to find the code that generates each link to a category (there are probably less of them than you'd expect) and tweak the parameters passed to the function that calls then to add 'target="_blank"' to each one. That would cause it it open in a new tab or window.

That said it's a really bad idea. This is not how sites usually work, and would be both confusing and irritating. Many people will completely miss the fact that you've opened a new tab in their browser and just think your site doesn't work. And it goes against the best practise, which would say that users already have the option to right click to view the result of a click in a new tab or window, by forcing it, you deprive them of an option.

Ok, then I won't do that. But I some how need to figure out how to do this...

This is the site:
http://www.project-hope.info/store/

When someone clicks on "Ring Designer" in categories, I'd like it to open this:
http://www.project-hope.info/store/RingMaker/index.htm

I'm just now sure how to do it now.

Once they have designed their ring, how are you going to get the programming to "add to cart"?

No idea. Frankly the guy that I'm putting this together for doesn't even care. He just wants it there so people can see what they can do.