You need to connect the audio outputs (red + white cables) plus video output (yellow cable or svideo cable) from the output connectors of the FiOS box to the input connectors of the VCR. Then you have to go into the setup of the VCR to make sure it knows to use those connections.
You can get the yellow/red/white type of audio/video cable at most places for just a few dollars (Walmart, Target, Radio Shack, etc.).