I found this information on pages 68/69 of the user manual:
Make sure that the storage card is properly installed on your phone. Check Chapter 1 for details.
Select Start > Applications > File Explorer and navigate to the appropriate folder.
Select the file you want to copy, then select Menu > Edit > Copy.
Select Up until you get to the root folder (My Device) and then select Storage Card in the list.
Select Menu > Edit > Paste.
Please let me know if you were able to move your files based on these steps!