How did the English Civil War lead to the rise of the Commonwealth?

the English civil war was won by Oliver Cromwell (a member of the parliament) who was fighting for democracy. since he won the war, the parliament executed Charles I because of the charge of treason against him. England eventually became a democratic government. at first, the parliament ruled the country, but eventually, they couldn't seem to do the job, so they asked Oliver Cromwell to rule the country, since he was the most enthusiastic suitable and for the job. Oliver Cromwell refused, because he didn't want to have had killed the king just to take his place as king. so he ruled as the government, and kept England democratic...