From the HD2000 User Guide:
Simple Networking: This method provides an easy way to update BrightSign devices remotely. Create a BrightSign folder on your web server, place your new content in this folder, and then use BrightSignÃ¢â‚¬â„¢s Windows tool to create a sync file, so the BrightSign knows what's changed in the folder. When you use the NetworkTimer command in your playlist, BrightSign automatically downloads the content you place in your network folder.
Where do I download the "Windows tool"?