Navigate to the section you want to restrict access to.
From the toolbar, select Options > Restrict access.
Verify the Private radio button under Page restrictions is selected.
In the User or group text field, start typing the group's name. Once the field populates the group's name, select it and click Add to list.
Click Apply restriction settings to sub-pages and choose the appropriate option.
Click Save permission settings.
New sub-pages automatically inherit the restrictions of their parent pages. You will NOT need to individually set restrictions for every new article you create under a restricted page.