Short answers, pulled from the story.
Winston Churchill first publicly suggested the idea during a BBC radio broadcast on the 21st of March 1943 while the Second World War raged across the continent. He later stood before the University of Zurich on the 19th of September 1946 to declare that creating the organization would be a stupendous business.
Ten states signed the Treaty of London on the 5th of May 1949, establishing the organization with Belgium, Denmark, France, Ireland, Italy, Luxembourg, the Netherlands, Norway, Sweden, and the United Kingdom as founding members. Greece and Turkey joined three months later to complete the initial group.
Thorbjørn Jagland was elected Secretary General on the 29th of September 2009 and became the first to be re-elected in June 2014. He currently serves as the head of the organization after previous leaders like Paul-Henri Spaak resigned from their roles.
Russia lost voting rights in 2014 after annexing Crimea from Ukraine following support for separatists in eastern Ukraine. The Council suspended Russia completely on the 3rd of March 2022 after launching a full-scale military invasion of Ukraine and terminated its membership immediately under exclusion mechanisms.
Unlike the EU the Council cannot make binding laws but produces international treaties like the European Convention on Human Rights. Member states maintain sovereignty while committing through conventions developed together at the Council whereas the EU transfers powers from national to EU level.