Most production companies will not accept unsolicited manuscripts for legal reasons. You need to submit your manuscripts to agents and get an agent or entertainment lawyer to represent you. Unless you have representation from a signatory agent or attorney, a production company or independent producer will not look at your work. The reason is that if, say, you submit an idea to a production company, and they turn it down, if years later they decide to make a show that is even slightly similar, you might sue them. That's why it's standard practice to reject unsolicited material.
You can get a list of agents from the WGA and start submitting to them. Remember the while you can register anything you want with the WGA, you cannot legally copyright an idea or a concept. You can copyright your manuscript in which you describe your idea, but what you are registering or copyrighting is not the idea, it's the language. Unless it is as fully fleshed-out as a script or very detailed synopsis, it will fall under the category of 'concept' and that is not something that is protected under intellectual property law.
Generally speaking, however, reality programming is created in-house, which means that the company or producer themselves come up with the ideas, rather than looking for pitches from the outside. Networks will also come up with ideas themselves and to to the company or producer to create the show.
I'm not trying to discourage you, I just want you to understand the process as much as possible.
