In order to give someone a role on Facebook Page you must have admin access.
If you are an administrator then it simple to add ta person to be able to access the Facebook Page:
1. Firstly click “settings” at the top of your Page.
2. Click Page Roles in the left column.
3. Now to add the person:-
If the new person is your friend on Facebook as you begin typing their name you can select it from the list that appears.
If the person is not a Facebook friend then type their email address that they have provided you.
4.Now select the role from the dropdown menu.
Admin – Total Access
Editor – Typical access for Marketing or SEO Company
5. Click Save and then enter your Facebook password to confirm these actions.
The new person may receive a notification or an email once this step is completed.