Develop your sitcom and write a pilot script. Before you pitch a television idea, you must have an idea to pitch. The story should have enjoyable characters that people can relate to, a clear storyline and the ability to generate stories week after week after week. And since it is a sitcom, it should, of course, be funny.
Register your script with the Writers Guild of America. This will help protect your rights to your material and prevent it from being easily stolen or re-written.
Identify the market for your sitcom. Not every sitcom is right for every channel. Watch a variety of shows on a variety of networks to identify which network produces sitcoms of a similar tone, style and demographic as yours.
Identify agents, managers, producers and executives who produce content similar to your sitcom. Just like your sitcom will not be right for every network, it will also not be right for every buyer. Since the buyers are the people you need to convince to read and green-light your script, make sure you target people who work with material like yours.
Watch the credits of similar sitcoms and write down the names of the producers and writers involved in the show. Look up those producers and writers online to identify their agents and get their contact information.
Query agents, managers, producers and executives. Send a short email or letter to potentially-interested parties. The email should include the basic information about your sitcom and a bit about your background and training as a writer. Because agents and producers get so many letters, you should send out emails to lots of contacts and you may not hear back.
Do not send your script at this stage. Wait for them to request it.
Follow up with contacts. If anyone requests to read your script, send it to them right away and follow up in a couple of weeks if you have not heard back.
If an agent likes your script, she will send it to producers for their consideration. If a producer likes your script, she will send it to the network for final consideration.
Consult an agent or lawyer for contract negotiations. If the network decides to buy your sitcom, you will need a good agent and an attorney to make sure your rights are protected and that you get fairly compensated.