Custom Opt-In Pop-Up Page

I'm developing a blog where I want a pop up opt-in box to appear within 5 seconds after the visitor arrives at the home page. I purchased a wordpress plug-in Action Popup for this purpose. It had a number of features that made it stand out from the competition - namely the thank you page would appear as soon as the customer opted in without the customer being taken away to another page. What I need is a simple pop up opt in form with bulleted text ? containing my sales message. This will be integrated with my Getresponse account. Would also like that feature of Action Popup that will keep the visitor on the home page during the whole process. And if possible the dimensions of the pop up to be centered, above the fold,? take up less? of the visible screen as possible without visitor having to scroll, and contain the full message? I need help as I am running out of time and I don't have time to figure things out.... My HTML? / CSS skills are minimal. Thanks.