eRA Commons is the portal used by grant applicants to submit their applications and track all the administrative requirements for their grant throughout its lifecycle. Unlike with other portals, you will not create the eRA Commons account yourself; an institutional official registers your institution and then creates accounts for members of the grant application team. It is at this point that you would enter your information.
When you are at this point and ready to learn more about managing your eRA account, watch this 10-minute video: Maintaining Your Personal Profile, created by the NIH Grants Office.
You can also find information about each section of the personal profile here: Personal Profile Module.