Your PC as in your desktop?
The 770 doesn't work like a Pocket PC. You don't have to install apps on your desktop PC and then 'sync' them with your device. You install them directly onto the device. Use WiFi to get online (or your phone if you are one of the lucky ones whose phone talks to their 770) and open up the web browser on the device (top left world icon), and navigate to the address mentioned above in a previous reply. That should then prompt you to install.
Good luck.