how w e can start to learn hypnosis...  

I recommend taking a class on hypnosis. Inducing hypnosis is relatively easy, it is what you do afterward that really matters. Hypnosis is a valuable tool for self change. It can help release unwanted behaviors and create new ones. It is NOT mind control. You will not be able to make anyone do what you want them to do...unless they want it too. The subconscious mind is always present and will not let suggestions in that are against a person's moral values, or outside of their personality
As I said, hypnotic induction (hypnotizing) is pretty easy to learn, but if you dont have a background in psychology or counseling, please take a good certification course so you know what you are doing. There are many people out there practicing hypnosis who really don't know what they are doing.
There are distance learning courses you can take if there are no schools near you.If you want a list of schools, send me a private message.
I have been a hypnotherapist for 17 years and I love my work. I have worked with many interesting people with some interesting issues :) Happy studying!!