You will find the organizations page as the last page in the left navigation menu on the main page.
If you are part of an organization you will be able to find it on this page.
Regular users are usually not part of an organization.
Users that have the ability to make new projects are often owners of their organization.
Users that have the ability to archive projects can also have access to an Archive organization to which they can transfer projects.
Transferring projects to an archive organization will free up a spot in the main organization so new projects can be made.