In order to publish an Action on the Google, you will need to first create a project within the Actions console.
There are two main routes when creating a project which depend on if you want to use Google's NLU Dialogflow in a way that is tightly coupled (all calls go through Dialogflow) or use an Actions SDK package which will require you to bring your own NLU.
Most likely, you will want the Dialogflow option as it is easier to work since everything can be configured through a graphical user interface and provides other channels in addition to Actions on Google. The Actions SDK will require usage of a command line interface but does allow you to use another NLU.
Setting up a project for Dialogflow (most popular)
The instructions Google provides in their documentation is the most complete and thorough. They can be found here.