You can find out more information here:

https://en.wikipedia.org/wiki/Nelson_Mandela

I can also recommend an Oxford biography:

http://fdslive.oup.com/www.oup.com/elt/general_content/global/readers/Nelson-Mandela-Factfile-Chapters-1-3.pdf?dm_i=1MVU,6WYLY,A189SL,RSK5M,1