My greatest weakness

I do believe that my greatest weakness is the fact that I just cannot talk to people, even about things that are so very important to my heart. Today I went soul winning with the church. I don't do the door to door knocking due to me being so shy and unable talk, I go putting tracks on doors without knocking...that seems to be comfortable enough for me. Well, today there was a guy sitting outside in his yard smoking his cigarette...I immediately stiffened but tried approaching him as casual as I possibly could. I had my little sister and a friend following close behind me. finally I approached and said as joyfully as I could, "Hi, we're from Calvary Baptist Church and we're out inviting people to church. Can I give this to you?" he said yes, so I gave him the track and told him to have a nice day and turned around and started walking away. Before I got anywhere he said "Is that it, you don't have nothin special to tell me?" I froze right where I was then turned around slowly. I was thinking "this guy is going to challenge me, huh?" I was scared out of my mind. "What do I say to him?" I thought. I walked back towards him and said, "Well, Jesus loves you very much, and-and-uh, he died on the cross for your sins and umm Him and I would love-would love to have you at church. What could I say ? I must have seemed so stupid to him! He began asking me questions that I had no idea about. He also asked what we as baptists believe...like if our doctrine is focused on John the baptist or something. I got to tell him that we believe in Christ, God's son, and that he came to die for our sins on the cross, he said that he believed that too. So I just finished with "our church teaches strictly from the Bible. We would love to see you some day if you can make it. Have a nice day." And we all went walking on our way. How could I not even be able to speak about the Lord without freezing?! I just hope that God isn't too displeased with me. Well, I suppose this is just an issue I need to be praying about.