You are right up, to a point; God wants every believer to be a witness for Christ to those who do not know Him. Jesus said, "You are the light of the world. ... Let your light shine before men, that they may see your good deeds and praise your Father in heaven" (Matthew 5:14, 16).
But witnessing for Christ isn't just a matter of speaking to others about Him although that is part of it. We also witness for Christ by the way we live and this often makes a greater impact than our words. After all, we may tell someone that Jesus can change their life but how do they know it's true? They will know it's true when they see it in our lives. They will realize that if Christ can change our lives, He can change theirs as well.
Do others see Christ in your life? Do they see His love and compassion as you deal with other people? Do they see His patience and peace as you face difficulties and hardships? None of us is perfect but ask God to bring you closer to Himself, and to change you from within. Ask Him also to fill you with His love, and help you to begin to see other people through His eyes.
Then ask God to help you tell others about Jesus whenever He opens the door. All around you are people who need Him, and yet are reluctant to admit it. Ask God to help you overcome your natural shyness and point them to Jesus.