If you are worried about someone you could try to talk to them, in private, about the problem. It’s important to let them know you are there for them and listen to them if they want to talk. Tell them about ChildLine. Get them to read these web pages with you and to use them to get the help they need.
If they are in trouble, or someone is hurting them, then you should tell someone you trust about it. Tell someone you trust so your friend can get help straight away. It is important that whoever is hurting them is stopped as soon as possible, as they may be hurting other people as well as your friend.