Short answers, pulled from the story.
Richard Whitman was a Korean War veteran born in 1926 who killed his commanding officer during an ambush in Korea. He stole the dead officer's identity to assume the name Don Draper and escape a court-martial.
The Mad Men series began in March 1960 and the pilot episode aired on the 19th of July 2007. The series concluded on the 17th of May 2015 after 92 episodes.
Peggy Olson started as Don Draper's secretary before rising to become a copywriter. Her journey represented a struggle to find her place in a man's world and inspired a generation of women.
Don Draper created a false identity to escape a past where he accidentally killed his commanding officer during an ambush in Korea. This fabrication allowed him to enter a new life as a white, wealthy, and successful advertising executive.
The Mad Men series ran for seven years from the 19th of July 2007 to the 17th of May 2015. It consisted of 92 episodes that followed Don and his colleagues through the 1960s.