If you are looking to play the Blues then you have probably been looking at some Blues Guitar instructional books you can get from Amazon or other stores online. For most subjects then getting some books to help you learn is an excellent option, but guitar is different because it is hard to explain how something as physical as the finger movements on the guitar needs to be done with just pictures and text.
If you want to learn to play the Blues then really you need to find someone to teach you, that is the absolute best way as they will show you what you need to do, and as you are learning they can keep an eye on you and help you out when you are struggling. However, that is expensive, lessons can cost 30 – 40 dollars a time, and you will need lots of lessons to get good.
You might want to consider a DVD course though, they are not as good as lessons, but they are a lot cheaper and also a lot better than trying to learn from a book. That way you can watch what the tutor is doing, how they hold the guitar, how they move their fingers, and what the end result sounds like. They also usually give you close ups of the fretboard for tough bits, so you can see exactly what they are doing, which is a real step up from following along with pictures in a book. So you have a few choices there, if you have the money spare then you can opt for lessons, or you could buy one of the many DVD courses available, or even try to find a membership site online which can help turn you into a Blues legend.