Evangelism is basically sharing the good news. What better news is there to take? than the message that God has made a way for us to be reconciled to him? While specific people are called to the full-time ministry of evangelism and we are all called to reach and share the gospel with the un-reached communities.
Evangelism is about our willingness to "GO". Then I heard the voice of the Lord saying, "Whom shall I send? And who will go for us?" And I said, "Here am I. Send me!" (Isaiah 6:8, NIV). Evangelism point to our only source of Salvation and share God's goodness with all creation.