If your device isn't running Windows 10, refer to the Windows 8 instructions.
From the Home screen, navigate: Settings (located in the lower-left) > Accounts.
If the Windows Settings options are not visible, tap or click the Settings Home icon (located in the upper-left) to go to the Settings home page.
Utilize the touchscreen (if available) or mouse to select on-screen options.
From the left-pane, select Family & other people.
To set up Family/Child accounts, refer to Microsoft's tutorial.
To set up other users:
From the Other people section, select Add someone else to this PC.
Do one of the following:
If the person you're adding has a Microsoft account, enter their email address, select Next then select Finish.
If the person you're adding doesn't have a Microsoft account, select I don't have this person's sign-in information > Add a user without a Microsoft account.
Enter the user name, password and password hint then complete any remaining steps to finish account creation.