1. Go to Start > Settings > Accounts
2. Click Family & other people in the left sidebar
You will choose between a Family account or Other People account. The Family accounts are Adult and Child types. You would use Family accounts mainly if you want to manage a child's activity (time limits, track usage time, restrict websites, view visited websites, etc.) or if you need to restrict users from changing any settings, installing software, etc.
Otherwise you would create a regular account under Other People.
3. Under Other People click Add someone else to this PC
4. Microsoft will steer you to create a Microsoft login account vs. a local account, but you can click I don't have this person's sign-in information then click Next
5. To set up a local account click Add a user without a Microsoft account at the bottom
6. Enter the Username, Password and Hint then click Next
The account will be created as a Standard Account. You can click on it to Remove it or change the type to an Administrator account.
To modify other options on the account you will need to login with that account.
Each user has their own Start Menu, Desktop, Documents, Pictures, etc. Only an Administrator type account can access other user's profile folders or copy files between them if needed. ( C:\Users\accountname )
Steve