If you want to know how to witness then the following sermons are excellent:

1) Open your Eyes to Soulwinning Keith Daniel 

An amazing challange to the christian to love and therefore witness.

2) The Dynamic Soulwinning Seminar Roy Daniel 

This is a seminar presented by Roy Daniel who is a South African Evangelist Son of Keith Daniel. He has quiet a few years experience in street evangelism, evangelistic preaching and one on one soul winning..

3) Salvation Crystal Clear Jerry Mahor 

This is an amazing sermon that God has used to save many souls. If you want to know what the gospel message is then listen to this Biblical sermon to have a good idea of how to explain it to someone.