A good place to start is by getting a complete setup like those sold as a set like the Attitude goggles with a camera and a vTx, basic but will get you FPVing at a reasonable cost and with reasonable performance.
Later you can play with antennas, different frequencies, better cameras, better goggles, diversity, tracking, etc, etc, etc.
This will get you going http://hobbyking.com/hobbyking/stor...m_w_Trinity_Head_Tracker_and_CMOS_Camera.html
Pete
@petedee thanks for posting this. Does this kit have everything needed to put FPV on your quad?