When you connect fiber there are two cables. This is assuming you understand the different types of connectors and cables and instead focuses on you connecting the fiber strands to your Media Converter. The MC is a small box that converts the LED light to ethernet. The box will have both a GBIC connector and an ethernet port.
But which cable goes in the left or the right port and does it even matter? Yes, it does!
One cable is transmitting and one is receiving signal. To discover which is the transmit and which is the receive fibers: Remove the fiber connectors and look inside the SFP (GBIC) with your iPhone camera. One side will have a small red laser light (TX) and the other will be dark (RX). Now take your phone again and look into both ends of the fiber patch cord. One strand will have a small red laser light (TX) the other will be dark (RX). Make sure that the Transmit (TX) fiber strand is connected to the receive (RX) port on the SFP. If you need to reverse the fiber strands, the small clip that holds the two connector ends together can be removed, the connectors reversed, and then clipped together again. Be careful with the connector, it’s generally easy to break it.