Small PHP Application / Class

I have a php script which i have written myself and i works great but the coding is very messy and scrappy and i want a nice clean PHP application written to replace it. The application is for use on an address management site. This is what I need the application to do: Validate the account details submitted against the DB Check the account has credit Perform a search of the DB for the submitted query if there are not result perform a C-url request to an external domain and add the new data to the DB Display data in a format specified either JSON or XML -1 credit from the users account.