You will need three connections: +5v, 0v and a SERVO output signal. On that board (I assume you mean the AXE117 - it helps to say what module you're using), you need to connect to one of the output pins which are accessible between the 14M2 chip and the ULN2003A. Don't use an output of the ULN2003A as these are an open collector connection. Refer to Manual 3, Output Device 8.