I just got a project to develop a currency exchange website just like naira4dolar.com however the basic thing I know about how the front end works. ie from the user perspective is to make payment into their bank account and submit the teller details to have their account credited
Now, the backend system is a little bit shady.. will all staffs start checking through their systems to see the latest credit alert and to immediately update the creditor's account? how can this system manage thousands of users, maybe I don't have the knowledge of the back end.
I will appreciate if someone can explain to me.

Get someone to do it for you.