BLE Control for Arduino App query

I got an HM-10 bluetooth module and can connect to it via my iPhone. The BLE Control for Arduino App allows you to program various buttons but I cannot fined how to do it. For instance it says that the command to turn pin 13 low is "d13 l" but nothing happens. I think I might be missing something out but I don't know and cannot find any info, anywhere. Can anyone help please?