If you really want to learn the Blues then you can get lots of Blues books off Amazon.com. Often they come with a CD as well which has someone playing the technique before you try and learn it yourself. You can learn from a book, as long as you are a good guitar player before you attempt it, if you struggle playing the guitar anyway then you might struggle with all the new techniques and concepts, in which case having someone there to explain things and help you when you make a mistake would really help you to learn quicker.