To edit a file and save the file directly to DriveHQ online storage, you must open the remote file from DriveHQ FileManager. The file is automatically downloaded and cached in a local cache folder. It then launch external application such as Word to edit the file. When finished, simply save the file in teh cache folder, it will be automatically sync-ed back to DriveHQ.com online storage.
If it does't work, please provide more info. You can also use the Folder Synchronization feature to sync local and remote folders.