In 1859 the was a escaped slave named Dangerfeild Newby. He was part of a raid in Harpers Ferry, Virgina where 25 men (including John Brown) raided a gun supply in Virgina. Well some lonely drunk guy was walking by and saw them raiding it and ran to tell everyone. In about 30 minutes the hole town had their guns and were at the gun supply building. John and his men locked them selves in the building and shot out of it. As they were fighting poor old Dangerfeild stuck his head out of the window and got shot in the head(headshot) and someone said "what a newby" and now the word newb means the same but spelled differently(noob) that is how we got the word noob.
(its a true story, but thats what i like to think how the word noob started)