Design the Windows forms Of the Program

Personally I start off by drawing a rough sketch of all the forms on a piece of paper. The I would start a new project in your preferred IDE and actually start the design. I know that in some instances you would not be able to draw the form due to controls being created and displayed at runtime, however you could still create them for design purposes. When ready, you can just take screen shots of the program while it is actually running. It is important that you don't include any code. Just the user interface. If you cannot produce a particular screen, you can always use an image editor to modify the screen shot and produce whatever form you would like. You don't need to be a professional designer, even with the use of Microsoft Paint you could easily perform such editing.

Hope this helps.