Organization Principals (or Organization Participants) are Windchill objects that represent an organization object in the LDAP (e.g. o=PTC). You can create them in two ways:
1. Site > Utilities > Participant Administration > New Organization (Note: this does not create an organization context. Organization contexts are the objects to which Products, Libraries, and Projects are associated.)
2. Navigation bar > Browse tab > Organizations > View All > New Organization
This is where you create an organization context. You can either create a new organization context and principal by specifying a unique name for Organization Name, or you can search for existing organization principals and create a new organization context associated with that principal (Note: only one org context can be associated with an org principal).
There are a few topics in the Windchill Help Center that discuss how to create/manage these objects as well as organization contexts:
"Creating a New Organization Participant"
"Creating an Organization Context"
"Organization Administration Overview"
If you don't have access to the above links you can always find the same topics in the Help on your own Windchill Server (Quick Links > Help > Windchill Help Center)