you can buy a kit at pretty much any craft store or a place like wal-mart. They're cheap and the spell it out for you they have a handbook with different designs. It's really easy and I think it's fun.
Alot of those kits have pretty cheap dyes. If you'd like to make something that lasts, check these folks... http://www.dharmatrading.com/html/eng/529065-AA.shtml Very high quality dyes and materials. I've done 2 sets of flannel sheets with their dyes and they havent noticably faded thru their lifetime.
im gunna be honest and try not be be cocky but im pretty good at it. iv made many different patterns so if you need any tips or how to's let me know
http://www.hipforums.com/newforums/showthread.php?t=440798&f=176 Check out my stuff. You are welcome to email me to inquire about the gobs of stuff I have that hasn't been listed yet. I hope you find what your looking for, wherever it may be.