Theming marketpress with spirit theme

Hello everybody,
In the past few days I'm trying to customize my single product page, I've already read the MarketPress documentation about how implement custom pages, but I'm not able to get the results that I'm expecting, so I'm calling for help;

Starting from the beginning,

What I want to do?
I want to fully customize my single product page, reorganize the content, keeping my UpFront header and footer.

What I have to do?
Can you guys give me some guidance to accomplish this? I'm really confused about somethings and how to do it;