The purpose of the Virtual ports is explicitly mentioned in the application. You can use the Virtual ports for creating an independent data connection between your broadcast automation system and the RDS encoder.
If your broadcast automation system is installed on another PC and provides now-playing data via serial port and the PCs are connected by serial laplink, then your use is correct. Otherwise it makes no sense.
More likely the now-playing data is provided via TCP or via text file (for which the appropriate tool is the External Text).
A need for a simple step-by-step manual is quite understandable but not applicable at all. Each radio station is unique in the hardware and software solution as well as in the network topology. For each radio station, the setup is strictly individual. I would recommend to contact some local IT experienced person or the broadcast automation system community or use (paid) services of some local FM broadcast equipment vendor.
