If you are wanting to use the touchpad instead or carrying around a mouse, you will need to enable tap-to-click for the touchpad emulate mouse clicks.
1. Go to the upper-right corner of the screen and click the wrench icon. Select Settings from the drop down menu.
2. In the left pane, select System.
3. In the right pane, go to the Touchpad section and check the Enable tap-to-click checkbox.
4. Close the Settings tab.