There is a wealth of material about Yuri’s life on the internet. He was born in Klushino on 9th March 1934 and died aged just 34 in a still-unexplained plane crash on 27th March 1968. He became the first human being in space on 12th April 1961 when he flew aboard Vostok from Baikonur cosmodrome in the Soviet Union (now Kazakhstan), but there is far more to him than these three well-known dates.
To learn more about Yuri, see the Wikipedia page. If you want to dig deeper, there is also a fascinating and detailed biography, Starman: The Truth Behind The Legend, by Piers Bizony & Jamie Doran, which you can buy here.
For a detailed account of Yuri’s legacy and other events to celebrate the 50th anniversary of his flight, see the excellent resource at YuriGagarin50.
The April edition of Sky At Night Magazine has two articles by Gagarin50‘s Richard Evans on Gagarin in Britain and Evans’ trip to Star City in 2010, the place where all cosmonauts have trained since the 1960s. Find out more here.