From the Home screen, touch and hold the Recent Apps Key (in the Touch Keys bar) > Settings > Storage > the Menu icon (at the upper-right corner of the screen) > USB PC connection.
Tap Media sync (MTP), Internet connection, or Camera (PTP) to connect to the PC.
Tap Charge phone to use only the charging function and not the USB function. It also allows you to safely disconnect your phone from your PC.
The MTP driver may not be installed on your PC by default. The driver is dependent on the PC's versions of Windows® and Windows Media Player (WMP).