Trying to restart, but can't quit Safari.

I am trying to restart, but am told to quit Safari, which is greyed out. So not an option.

Keep reading to engage "option" button, among others, but I don't have an option key.

My keyboard is designed to work with either Mac or PC/ I am on an iMac. Need to restart,

because I keep getting beachballs on my screen.

How to do this?

https://www.youtube.com