There is a really good little maybe 3 minute tutorial on the jinny beyer site on Y seams. she shows how to do them by machine and how to do them by hand. I think it makes perfect sense when you watch it live
if you can get away from checking out all her gorgeous fabric. If I won the lotto it would ALL be mine! I had never seen her stuff before but wow. still havent sat down to do this yet. lucky for me the month is still young.