After you've installed the Bluetooth drivers on your Pocket PC with ActiveSync, tap the small keyboard icon in the lower right portion of your screen.
This will be the next screen that pops up. Tap the "Enable" button.
Ensure that the "Bluetooth wireless keyboard" radio button has been checked and tap the "Setup" button.
If you have not done it already, open your Bluetooth keyboard. Ensure that the "Secure" checkbox beneath the "Connect" button has been checked and tap the "Connect" button. If there is no green light flashing on your Bluetooth keyboard, hold down the "Ctrl", left "Fn" and right "Fn" keys until the green light begins to flash.
After a few seconds this screen will pop up. Using the on-screen keypad, type a numeric passkey that you will use for your secure connection, and then tap the "Enter" key on the on-screen keyboard, or the "ok" button in the upper right hand corner of the screen.
This is the next screen you will see. At this point type the same numeric passkey into the Bluetooth keyboard, making sure to hold down the left "Fn" key in order to access the numbers. After you have done this hit the "Enter" key on your keyboard.
After all of that you will come to this screen, signifying that you have correctly set up a secure connection with your Bluetooth wireless keyboard.