can you screen share with a non mac computer

I don't know for sure what you mean by screen sharing. I can tell you that I have been able to see and control remotely my brother's PC screen by using an application called TeamViewer. This is password protected each time it is used with a randomly generated password. He can also access my iMac if he so wishes. We merely have to reverse the log-in procedure. The application is very easy to use and seems very secure. It works, obviously, on a Mac or PC and was first recommended to me by my computer literate nephew as a means of him being able to help me with some computer problem I was having at the time.