Okay, so ive seen sites like Blackmarket Reloaded, flexcoins, My Wallet and more. Whats interesting is their eWallet where each user can store his/her bitcoin in their account. I have a small website and Id love to implement a feature like this but I have no Idea where to even start.

Can anyone guide me? I hope this is not too complicated as I really never deal with website programming and only programmed programs.

Thanks!