Under Settings -> Mouse & Touchpad -> Additional Mouse Options, there should be an option/tab like Device Settings or Cypress TrackPad.
For Synaptics, click on the Device Settings tab, click Settings and on the left side of the window should be an option that says Pinch Zoom, click that and then check Enable Pinch Zoom and click ok.
For Cypress TrackPad, click on the Cypress TrackPad tab, click Click to Change Cypress TrackPad Settings, then click on the 2-Finger Gestures tab and check Zoom In/Out and click ok.
If these don't help you out, you'll need to provide more about what Laptop you have and maybe someone else can give you some more help.