Here you have the solution for the simple exercise in the book.
When keep on thinking on how to draw the lines, it’s very difficult to see the solution. If you first start drawing from A to A and later from B to B, you’re well on your way to the solution. The best way to find C to C is to just start drawing the line until you bump into an other line. Change direction and keep working to an open space. Only then you will find the solution.
Sometimes you just have start working without knowing all the details.