Need help starting up!

Hi guys,

I just bought the marketpress plugin and Im having real trouble starting up the whole thing. I basically want to:

1.put a single product(ebook) on the sidebar, so the customer can see it.
2. The customer reads the single page of the product(I dont want no store, Just the page where the single product is displayed). Decides to download it and hits the buy it now button.
3. After he hits it, I want marketpress to ask the customer directly about his bank details(I setted up paypal express already). I dont want wordpress to have like 2-3 confirmations, asking the customer is he done and stuff. Just straight to the point. Buy it Now-Bank Details!
4.After they enter their bank details or paypal and if its all good, a window popping up, letting them download the file.

I will be thankful to infinity if someone tells me how to do that stuff, because im starting to freak out. Im not really big on the technical side of Wordpress and starting this is KILLING ME. Can someone help me please?