Even young people can tell others about Jesus. When people ask you to do or say something wrong tell them no and that Jesus has taught you how to act. Then tell them about Jesus and how He wants what is best for us and wants us to go to heaven. Some people do not have parents who take them to church or tell them about Jesus so be sure to teach them with a kind heart. Never act like you are better than them because your parents have taught you well. Be thankful for good parents.
You can be a good example to others with proper manners, kindness, and being more concerned about others than getting what you want. This is the way Jesus lived and so should we.
Another way to tell people about Jesus is to invite them to Bible classes, church services, and gospel meetings. I knew of some adults that attended because a child in their neighborhood or school invited them!