Each rubric has a "share rubric" button at the bottom of the Edit Rubric page.
Alternatively you can click on "my rubrics" at the top right. This will list all of your rubrics. There's an "edit" and "share" link next to each rubric.
On the rubric's sharing page you'll see a "public link" that you can share via email, twitter, etc. to allow others to view your rubric. Anyone with the link can view it; they do not have to be EssayTagger users.
Each rubric also has a "rubric code" such as "Y2-E8CM". EssayTagger users can enter this code to import your rubric into their account (go to the "add a shared rubric" tab of the "my rubrics" page). This is a key way for teacher teams to coordinate and collaborate. One team member can create the basic rubric structure and then share it with each teacher on the team so that everyone is using the same rubric template to evaluate an assignment.