ABAP Proxy

I am trying out for File to ABAP proxy scenario.I had created all the stuffs in design part and in my ID part i have created a Business Service for the sender and a Business System(R/3) for my reciever.In the Business service i included the Mssg interface of the source in the sender's tab,but i don't how to add the Mssg interface of the reciever in the Business system(R/3) and without this i can't run the wizard.Can Someone help out how to proceed?