Custom Modal Popup

I will start out by saying that I know nothing about modal popups except that they are cool. I don't even know if this is possible but I thought I would ask here and see what it would cost. I am looking for code that will write code to, and open a modal popup. The code must be inserted into a smarty PHP template so it should work with literal tags. It must pick up a variable within a URL from the smarty template and write that to the popup. The popup will have a button that when clicked, closes the popup and redirects the parent page to the URL with the variable. I have created a working example with regular javascript but it is outdated code, and not as cool. You can message me for the link to the example as it is on an adult xxx website domain. (no nudity on example though)