For your changes to be effective, you'll need to force Amahi to regenerate the greyhole.conf file. You can do so by editing a share, clicking it's path, and just clicking the Save button without actually changing the path.
== Copying data into to shares for the first time ==
When you start using Greyhole, you might want to copy or move all your existing files into your new shares that use the storage pool.
You're done. All your existing data is now stored in the various drives included in your storage pool, and are accessible via the Samba shares you have defined in the Amahi dashboard.
== Adding a new drive to your HDA and storage pool ==