Mockup the Screens
Create a mockup for every screen needed in the system. This may start out as a storyboard, which would be helpful to understand all of the moving parts in the program.
Specifications and Project Plan
Build specifications and a project plan for the development team using the Scope and Requirements and the storyboard. Create a timeline based on resource usage.
Let the Coding Begin!
Now the full software development lifecycle takes over: Code, Test, Debug, Document.