how did Nelson Mandela help to the end of apartheid?

Since this is not my area of expertise, I searched Google under the key words "Nelson Mandela" to get these possible sources:

http://en.wikipedia.org/wiki/Nelson_Mandela
(Broken Link Removed)
http://nobelprize.org/nobel_prizes/peace/laureates/1993/mandela-bio.html
http://www.time.com/time/time100/leaders/profile/mandela.html

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.

I hope this helps. Thanks for asking.