Step 1: Select a File for Transfer
Sync your Pocket PC via ActiveSync (or Windows Mobile Device Center, WMDC, in Windows Vista). On your PC's hard drive, locate a .WAV file you'd like to use on your Pocket PC as an alarm sound. In this tutorial, we'll transfer the audio file "new.WAV":

On your PC, highlight the file you wish to transfer and click Edit > Copy.
In ActiveSync or WMDC, click the Explore button. In the Mobile Device explore screen, navigate to My Windows Based Mobile Device > Windows folder:

In the Windows folder, select Edit > Paste from the toolbar. The file you copied to your clipboard will be pasted to your Pocket PC's internal memory:
Step 2: Check the Alarm Sounds Menu
Now that you've pasted your .WAV file in the \Windows folder of your Pocket PC's file system, the file should show up as an alarm option. On your Pocket PC tap Start > Settings > System (TAB) Clocks & Alarms. Tap a bell icon to view available sounds:

To the right of the Play sound setting, tap the down arrow at the right of the drop-down menu. The audio file you transferred should now appear in the list:

If the file you transferred now shows up in the sound list, you're ready to set alarms.
Final Thoughts
Because of the way they're encoded, certain .WAV files may not work with the Windows Mobile OS. If you run into trouble, try another file.