Ok a Shaman is a person who has the ability to tap into the spiritual realm in order to tap into information and wisdom they would normally not be able to obtain in the material world.Also this person must venture out on what is called a Vision Quest.There are also those are able to safely pull demons or evil spirits from a person and dispose of this demon or evil spirit.The true test is if one can freely walk through the spiritual world with out being harmed by any.A lot of the shamanic relegion has been lost over the years,and to truely be able to learn and understand what true shamanism is you will not find it in any book,or in any new form of shamanism.
Those who are able to teach mostly will not if you are not from there tribe,but for a select few if these shaman see something in you they might teach you.It is a long hard road but honestly would it be worth it if it was easy.My grandfather taught me the way of the Shaman before he passed and know I honor him by helping anyone who will willing let me help them.
This is only a short version and not very detailed that will come later,But until then be safe.