To enable jitouch,

(Steps 1 - 3 may have already been done for you.)

1. Open "System Preferences"
   
2. Click "Security & Privacy"
   
3. Go to the "Privacy" tab and select "Accessibility"
   
4. Click the lock icon if it is locked
   
5. Check "Jitouch" and "System Preferences"
   
6. Close the window