simulate left click on touchpad (tapping?)

Hi, I have acer aspire one netbook with synatics ps2 touchpad. It works fine, but I’d like to emulate left button by just pressing somewhere in the touch area (same as it works in windows or ubunntu). I think this is called tapping. How can I configure that? I have been in touchpad settings and management, but I have not found any checkbox helpful. In OS 11.3 I need to press left button next to the touchpad.

If that is all you want, simply add the line
Option “TapButton1” “1”
to 20-synaptics.conf

Thank you, but it had no effect. Is this corrrect?

me@linux:/etc/X11/xorg.conf.d> cat 20-synaptics.conf
Section "InputClass"
        Identifier "touchpad catchall"
        Driver  "synaptics"
        MatchIsTouchpad "on"
        MatchDevicePath "/dev/input/event*"
        Option  "HorizScrollDelta"      "0"
        Option "TapButton1" "1"