If you are new to ORCID and are setting up your ORCID record for the first time, log in and go to Employment - Add Manually and start typing the name/s of your employer/s eg. Australian National University* in the Institution/Employer field and select it from the drop-down list. This will then pre-populate the rest of the first column.
All you need to do then is add your Department, Role/Title, Start / End Date and click on Add to List to finalize the process.
Repeat this for this for your other employers and don't forget to add your affiliations as well.
*While the University's official name is The Australian National University, and should be used whenever possible, the default option here is acceptable.