Short answers, pulled from the story.
The Declaration by United Nations was first signed on the 1st of January 1942 by the Big Four, followed the next day by representatives of 22 additional governments. Between 1942 and 1945, a total of 47 national governments signed or acceded to the declaration.
The declaration was drafted on the 29th of December 1941 at the White House by US President Franklin D. Roosevelt, British Prime Minister Winston Churchill, and Roosevelt's aide Harry Hopkins. Soviet suggestions were incorporated into the text, though France was excluded from the drafting process.
Franklin D. Roosevelt coined the term "United Nations" to describe the Allied countries, proposing it as an alternative to "Associated Powers." Churchill accepted the name and noted the phrase had been used by Lord Byron in Childe Harold's Pilgrimage, Stanza 35.
A total of 47 national governments signed the declaration between 1942 and 1945. The original 26 signed on the 1st and the 2nd of January 1942; 21 more states acceded by the war's end.
Each signatory pledged to employ its full military and economic resources against the Tripartite Pact and its adherents, and not to negotiate any separate armistice or peace with the enemy. The declaration also committed signatories to uphold the principles of the Atlantic Charter.
The declaration became the direct basis for the United Nations as a permanent international organization. The UN Charter was signed by 50 countries on the 26th of June 1945, carrying forward both the name Roosevelt invented and the political community of nations that had formed around the wartime declaration.