Build a Web application for Mail Room

Hi, Need to develop a .net project for mail room management i.e., to collect and send couriers from various courier service providers and inform to the employees on the courier and postal received by mail and collect the couriers from the employees if they want to send. To send courier, manager approval is required where a mail is sent to manager for the approval. Will provide the entire design in css to implement the design for the project. Once completed the entire source code along with the design and database need to be provided back. C# and SQL Server preferable with 3 layer programming Thx