Acts 1:8

Acts 1:8 - But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth.

You are a witness. In your life you have seen and experienced something that God has done. If you have received Christ in your life you have undergone a change. That’s what God wants you to talk about. Tell people about your experiences with God. Make it personal because that is what will touch people.
I know that it sounds scary sometimes, but that is why God has given us the Holy Spirit. He is our helper and our strength in weakness. Let Him flow through you and guide you in all you do and say. And make sure you are a witness everywhere you go.
Notice as Jesus gave these instructions to His disciples He began with Jerusalem and then worked His way out to ‘the ends of the earth.’ Jerusalem was where they were currently at. Jesus was telling them to start where they were, at home, and then broaden their circle of influence.
If you are not being a witness to those in your home and community you have no business going to other places and ministering. You must start with those closest to you. Let your life reflect what God has done in your heart.
The bible says that people are saved by the blood of the lamb and the word of your testimony. Your testimony will lead others to Jesus. Make sure you are using it.