To create a Publisher record click on Publishers to list all of your existing publishers. There is a Create Publisher option at the top of your list of Publishers:
Once you click on Create Publisher you will be presented with the form to create a Publisher. You can complete the information about the Publisher such as Name, email address etc:
The Password and Username will allow the Publisher to sign into their Publisher Control Panel where they can view their own interaction with your Brand, for instance looking at Reports and setting up new Campaigns.
You can define the Type of Publisher that this will be (affiliate, pay per click, offline / print etc), this is used in reporting to allow you to group on the Types of Publishers you have.
The Name and Display Name are the other two required fields, the Display Name is your Internal display name for the Publisher, and the Name field will be shown on the Publisher Control Panel.
The other fields are optional but can be completed, once done press Create Publisher to finish Creating the Publisher record:
This will take you back to the Publishers list but your new Publisher will now be selectable from this list: