How did Boris Yeltsin becomes the first leader of the Russian federation?

Borris Yeltsin was elected by popular vote to the position of President of the Soviet Federative Socialist Republic in June 1991. He won 57% of the vote against with 6 other candidates. When the USSR was dissolved in December, Yeltsin remained in office, becoming the first president of the Russian Federation. He was reelected in 1996.