Anyone can suggest edits to a nonprofit's profile, similar to Wikipedia. You can do so by clicking the "Edit" link in the "Learn More" section of a nonprofit's profile. It is then reviewed and approved by a moderator.
If you work at the nonprofit, you can claim your nonprofit's profile by becoming an admin so that you can edit the profile without needing to wait for approval.
Once you're an admin for a nonprofit, you will see a building icon in the top navigation header which you can use to access the Admin Dashboard. From the Admin Dashboard, click on the “Profile” tab to make changes to your nonprofit profile.