Who was martin luther and what idea of his became the cheif teaching of the protestant reformation

Martin Luther was a monk in a Catholic Church and a lecturer at Wittenburg University. His idea was jurisdiction by faith alone. (I'm not in High School! Hope this helped!)

Martin luther was the person who created the 95 theses and he challenged the roman catholic church and their ideas. He also wanted to prove to the society how the church's teachings were wrong and how they were corrupt (that is what the 95 theses was about). 

i dont know about the second part of the question but i hope this helped a bit