Connect your iPhone to your computer with a USB cable to begin to sync it. Open iTunes on your computer and find the iPhone option under the Devices menu. Click the Apply button and they will sync together. If you would like to sync them with WiFi, see the instructions at http://support.apple.com/kb/HT1386.
To sync your iPhone to your computer start by opening iTunes. Then, connect your phone to your computer using the USB cable. Select the iPhone under devices on the left hand side of the iTunes software. Click apply to sync the two systems.