Region is a feature of the Master Edition, so it will be disabled it after 14 days trial. You can also try the following way:
Use WavePad to move through the file finding the beginning and end of each item. Select the item then select Edit->Copy To New. Finally use File->Save to save the new item as a seperate file. Repeat the process for each item.
Region is designed to help you do this kind of job more efficiently.