The author does not explain how to design, nor even the basic elements of design. Her instruction boils down to "look at what the professionals have done." For instance, on the subject of designing your own stained glass pieces, she suggests re-drawing any (or all!) of the 84 designs included in the book. Just keep re-drawing them until you get a feel for proper design. And on the subject of reinforcing your pieces, she suggests looking at how professionals have reinforced their works, and then experiment with different methods and products until you figure out what works. This is not helpful advice from a professional, this is the type of advice you might get from a novice pretending to know what they're talking about. Keep looking for a good design book.