I have a 640 also. Bernina has classes on mastering your machine. With these classes they have a guide book. Call the dealer and ask for a copy. It takes you through several projects.
I was told to sit down and read the book over and over, then go back and highlight info. As for embroidery it takes practice. For me it has been live and learn.
If I can help in any other way PM me. I don't claim to know a lot, but will give it a try.