Hello good members.
I am hit with a task, to build a functional Online Prepaid Calling Card website.

This site will allow customers to pay for and make international and local telephone calls.

I really don't know where to start, however, I have an idea of how the UI (User Interface) will look like.

Another drawback is although I have done programming in vb and java, I am told to use C#(C sharp) or ASP.Net which I have not used before, but I understand it's much like java and C languages.

Any Tips and ideas from anyone will be greatly appreciated.
Thanks in advance.
Giftx.