RemoteDesktopTwain consists of two components which are automatically installed when you install the product:
RemoteDesktopTwain Server: Most scan applications use TWAIN drivers to work with scanners. RemoteDesktopTwain Server is a usual TWAIN driver and can be selected in any TWAIN compliant application as other hardware drivers.
RemoteDesktopTwain Client: This component allows using your scanner on RemoteServer via RemoteDesktop application (in Terminal Session).
As you install RemoteDesktopTwain on both copmuters: client and server you can access to scanner from remote server. When you have everything installed you will not be able to find any executable file to start it because RemoteDesktopTwain is a TWAIN driver. To use it you still need scan application. As a rule scan applications have menu item like "Select scanner" which shows list of available TWAIN data sources.
Select RemoteDesktopTwain driver and press scan button in the scan application. RemoteDesktopTwain configuration dialog will be shown.
If you have installed RemoteDesktopTwain Client then RemoteDesktopTwain get list of scanners from it and you will be able to select scanner to scan on remote server. Please see Scanning topic for details.