With the redesign of the new timeline Facebook pages, making someone an admin on a page is kind of hidden now. You can use the admin roles section, but if you don’t know there email, you must have them like the page to do it. Follow the simple instructions below to see how to make someone an admin.
Admin on new Facebook page
Have the person like your page.
Login and click on the “Admin Panel” button on the top right.
On the bottom left of the panel where it says “New Likes”, click on the link that says “See All.”
Then click next to the person that liked your page on the “Make Admin” button.