Need Guidence on auction house design

Hey everybody, I’m working on a project ATM that I need some help with…
I am hoping to design an online auction house, like ebay, but I have a small dilemma I would like some assistance with.

OK the best way I know to explain my issue is essentially I don’t know how to create the system I want, and the best way to describe the system is by giving an example:

When a user places an item on my site, others are able to place bids on that item. When the user sees an acceptable offer he would finalize the transaction, at which point an email is sent to an address of my choosing, giving me the address of both the auctioneer and recipient, their telephone numbers, and the product in question with price information.

I in no way want any form of online payment to take place, I simply want a notification email giving me all the information I specified…

And so basically my question is how would I do this?
I really need some help with this, so if anybody is willing to take some time and give me some helpful guidance I would be very great full.

And if anyone is unclear of the system I have in mind please say so and I will try to provide a more concise description.

Thank you all 🙂

PS: This is for a pretty big internal assessment, so I could use any help anyone is willing to offer