This is the main documentation for Bow Simulator. The User Manual gives you an overview of the program features, explains all input parameters and simulation results and also contains some background information.
Bow Simulator allows you to evaluate specific bow designs, but it doesn't really tell you how to design a good bow. If you want to learn about bow design you could have a look at the following sources:
The Traditional Bowyer's Bible, Volume 1, Chapter 3: Bow Design and Performance by Tim Baker is probably the most complete work on this topic. All the common design decisions and their performance implications are explained in a very practical and understandable way.
SuperTiller by Alan Case is quite an impressive Excel spreadsheet that runs a complete static analysis of a user-defined bow.
Woodbear's Selfbow Design Sheet [zip] by David Dewey is also an Excel spreadsheet, but with a different approach: It calculates the necessary dimensions for a bow according to a user-defined stress distribution. This is a very interesting way to design a bow.
BowCAD is perhaps the only commercial attempt at bow design software so far. They started an Indiegogo campaign and at one point offered different kinds of licenses on their website. Unfortunately it seems to be gone now.