DLL programming for MetaTrader and XML

I need help with programming a dll for a client, for use with MetaTrader. The task is to allow me to call a function from within MetaTrader, and to use the dll to search a xml file for a specific piece of information and then return a value. I.e (MetaTrader) Calls the dll and sends two strings of information. (DLL) Connects to the server and looks in the xml after theese two strings of information. Returns a value if the specific information is found, else a zero. (MetaTrader) Receives the return value, for use in the program. The budget for this simple task is no more than 50$. If you're assigned the project, you will receive more detailed information that information the dll shall send/recieve/connect. Deadline is in the beginning of next week.