To add a manager or user to your Facebook business page the first thing you’ll need to do is log in to Facebook and go to the appropriate Facebook page. Then in the upper right hand corner, click on Settings and then on the left hand side look for Page Roles. On Page Roles, you’ll see all the various admins including the owner of the account. Go ahead and click here. If they already like your business page, you can go ahead and just start typing in their name or if they have not liked your business page, then you would want to type in an e-mail address and then once you’re done, click the appropriate role that you would like them to have.
If you’re not sure about the role, just click the ‘Learn More’ button right up here and then click ‘Save’. Once saved, you will need to enter your Facebook password. After entering you password and clicking ‘Submit’, the user will need to approve before they actually become an active user on your account.