To start a catering business you'll need your standard business license to operate the catering business then you'll also need a license that deals with food which is known as the Food Establishment License.
And then if you want to serve Alcohol through your catering business you'll need to get an Alcohol license.
To get the business license and Food Establishment as well as Alcohol license go to your local city hall and ask them about the licenses as they will get your licenses started or direct you to places that will.