eyesells

I installed my new OEM A 211 827 63 42 head unit and trunk mount DVD navigation to upgrade from the cassette player. Everything just plugged right in all the wires were there. The navigation module has three wires but I had two DSP black wires to use, one had a blue fastener on the end and it fit the module but I don't know what to do with the other black optical wire. I cant find any info on youtube or anywhere else with regards to installation or removal of the comand navigation module. I also need to secure it with a bracket of some kind. Any ideas?