How to connect my acer extensa 4620 laptop to my

You should have VGA out port somewhere on the left or the back side of the laptop. It is the only port your monitor's signal cable can be plugged in, COM ports are not present on 90%+ of the laptops. So plug it and look for the right key combo to activate, should be Fn+some F1toF12 key. If in trouble, try via the control Panel > Display to detect the monitor, set resolution, primary, etc. as desired. If the monitor's signal cable is DVI, check for an adapetr, maybe there is such, or for a VGA port on the monitor, and buy the required cable.