How do I add an admin to a facebook page if Im not friends with them?

[Norman]

Adding an admin to a page is easy but can be tricky. You first have to ask the person concerned to like your page (i assume you did that already). The confusing bit is that there's an 'add admin' button next to each new fan but all this does is open the admin setup screen with an empty selection. As you found out, this only finds persons in your friends list. To find a non-friend, you need their Facebook email address. Type in the email address and the person concerned should show.
You should finally be asked to confirm by your password. Do not add anyone else as a Manager as they can then lock you out of your own page, use a Content Creator instead.