The Controlled VIA selection is where you choose what lighting control system is controlling this light. You will also have to supply parameters specific to your type of lighting system, such as the house code for X10 devices, or the Channel for Lutron Radio RA. You could also add generic relay-type devices here that use an interface module like the gc100.
Port/Channel Number is your X10 house code and address. For example, B3 would be house code "B" and light "3". No spaces, quotes, or commas are needed.