Hello edms,
Check out script.filesystemobject from the documentation and search this forum for frequent treated topic.
Bascially, you initiate a filesystemobject. Get the root of the drive. Use .files collection to get to the files directly under it. After verified the file's extension is .doc, use copyfile to make the backup. Then use .subfolders to get to the subfolders. Repeat the procedure again until there are none subfolders.
regards - tsuji