If you see something online that's meant to hurt someone, don't "like" or share it. Think about how you'd feel if someone did that to you.
It's OK not to like someone. It's not OK to bully them.
If someone cyberbullies you, you may want to send a mean comment back, but it could make this worse. Instead, save the evidence and report it.
Being a good digital citizen means standing up for others. Take steps to help peers being cyberbullied (eg., post nice comments, sit with them at lunch, report the harassment, etc.).