Does this help?
http://www.hgtv.com/decorating/tumbl...cks/index.html
I think that's something you have to dive in then you will see how it all goes together.
It looks harder than it is. Use a lot of starch as you will be sewing on the bias.
Edit: Here's Marcia's book with or without rulers.
http://softexpressions.com/software/books/4K10015.php