The book you want is "Art and science of sails" by Tom Whidden. Out of print and might be hard to get. If you can not get it, you could check "Maximum sail power". As always, there is a lot of information to pick up in "High performance sailing" as well when you get as far as designing the sails.

I would reccommend that you do a crosscut sail first. Either in standard dacron or Maxx/Flex cloth depending on your budget and equipment. For assembling a Maxx/Flex sail, all you need is a good floor, some measure tapes, the supplies, a good scissor and a domestic sewing machine. I would have done the design first and got through that part before deciding on cloth and where to get it.