Market Press Theming

Hello, I am using the market press plugin for a simple WP based store.

I am looking for some additional documentation on how to theme the store pages and I can't seem to find anything useful. The only documentation I can find is a quick text file in the download files. Unfortunately this doesn't answer the questions I have regarding custom page templates.

The main problem I am having is I am getting a PAGE NOT FOUND error when I upload a page using the php file names specified in the "Themeing MarketPress text file.

I'm not sure what I'm doing wrong as there really isn't any documentation on this. What is the process to create a custom theme/page for each of the different store pages (cart, checkout, product page). I need more information on this but after searching high and low on this site have not come up with anything.