It looks like you are on a mac.. thats the wrong window to try and setup dual monitors. IF I am correct and you are on a mac.. https://support.apple.com/en-us/HT202351 check that one out. (or maybe some flavor of linux)
It looks like you are on a mac.. thats the wrong window to try and setup dual monitors. IF I am correct and you are on a mac.. https://support.apple.com/en-us/HT202351 check that one out. (or maybe some flavor of linux)