Please have a read of the attached Doc about MacKeeper. Again let me stress no matter what pop's up on your web browser when you are on the internet, Never install programs off the internet from a pop-up window telling you, "You have a Virus" or How to speed up your Mac.
Just quit the browser and reopen it.
Please install and run this program
https://www.malwarebytes.com/mac/
Please read the attached Document