the page located at the URL that you specified as the "link to your site" will be opened in a frame occupying the top 150 pixels of the page, while the page located at the URL that you specified as your main link will be opened in a frame occupying the rest of the space under.

there is a script that will popup the page located at the URL that you specified as the "link to your site" in the case where one of the framed window would break out of frame.

if you specify no link to your site, only the page located at the URL that you specified as your main link will be opened, there will be no frames.