Never chat with someone you don't know or haven't seen personally.
If you are being cyberbullied, tell someone you trust. Here is a site you can go to if you're being cyberbullied. https://www.childline.org.uk/Explore/Bullying/Pages/online-bullying.aspx
If you find a button that looks like this, and you are being cyberbullied, click the button.
Don't fight cyberbullying, as it will eventually overwhelm you.