Jeff is right. Almost every CCTV system now involves networking on some level. When I first started doing video work it was all analog: High grade multiplex VCRs, cameras, power supply, and enough wire to hook them up. Simple. Now almost everything is IP video based, hard drives, and offsite back ups. Networking is always a major concern when working over the companies (for whom your working) network. I did a covert system for a credit card company and they wanted me to set it up over their network so that the bosses could view it off site and at their desks. I asked how many much money came through their system everyday, they said lots. I advised that I did not want to screw with a network that transferred lots of money. I did however assist their IT guy to get it done. Don't take on that liability on systems that if disturbed will make you civilly liable in the future. The sky is the limit with this new technology and you have to learn it these days. All the training that I have gotten has been from law enforcement sources but have worked with private companies in the past. I learned a great deal working with those companies and would suggest that you do an apprenticeship or work part time for someone who does it everyday. I learn much more effectively doing the work rather than reading about doing the work.
I'm doing some work with android phones, converted to IP cameras, to set up a secure independent wi-fi network for quick to deploy surveillance systems now. An old android phone with IP webcam installed is a great way to get started with this stuff. Just look up "android IP webcam" on youtube and set one up. You can look at the videos and setup either a simple or complex system. Fun to mess with and you will learn something about IP cameras as well. You can also find IP cameras for cheap on ebay now. They aren't the best quality but they do teach you the principles of setting one up.
I have no special talent. I am only passionately curious.