Start with Organization in the main nav.
Find the employee you want to meet with.
See the 1:1 Notes tab.
Anyone can take 1:1 Notes with anyone else, not just managers on employees or other org-related employees.
You can also navigate to your own profile and use the 1:1 Notes tab there. Think of these as your personal notes, not related to your employees or other people.
See tips about Effective 1:1 Meetings.