How do I update the HTML page holding the ifram everytime the iframe reloads?

I have an HTML page holding an iFrame with a form. When the form is submitted, the next form loads within the iframe (i used an openURL function), passing the necessary values with it. However, what i really want is to use a function to open a new HTML page with the successive form and necessary variables. So i guess i would need to pass the variables through the URL string, is that correct?

The reason i want to do this is because I am using wordpress and dropping the form URLs in the body. However I also need unique content on each page that give directions about each form. Since only the iframe is reloading, I cant add custom text associated with each form (above or below)

Thanks