When I open my browser, sometimes ads just pop up on the side specifically sendori ads then videos just start to play. How do I get rid of these pop-ups?

Run your virus scanner and install and run the free version of Malwarebytes

Here is an explanation of what it is, how you probably got it, and steps to get rid of it. Anytime you install something, even freeware, watch out for the "recommended" installation and choose "custom" instead. That's where they sneak other installations of stuff you don't need by you. Always choose custom install when given the choice to see things you don't want. Remove Sendori adware (Virus Removal Guide)

If using mossela Firefox use a addblocker addon