Every employee (unless Disabled) has a profile page -- regardless of whether that individual has logged into the platform to claim it.
Interests and skills are added during the onboarding flow when a user first logs in:
Access your profile through the dropdown in the top-right corner of the platform. At the top of your profile page, click on the Edit Interests and Edit Skills links to edit or add more of each:
As during onboarding, you may also create your own interests and skills here. After it has been added to your profile, click an interest or skill to see which of your colleagues share it.
Also on your profile page, you may edit your email notifications and change your password (if you don't use single sign-on).