Click on the three dots on the right hand side of the page then go to restrictions
On the pop up window that will appear click on the drop down arrow to get the three restriction options for the page
1) No restrictions - means everyone van view and edit the page
2) Editing restriction - Means only those you give permission can edit the page, however everyone can view the page
3) Viewing and editing restriction - means only those you have given rights can view and edit the page.
To give people permission to edit and view the pages
start typing the name of the person, select the permission you want them to have (either can view or can view and edit) and click add
Click on Apply
