How do I make another member an admin?

Click 'Members' in the main menu.

Click on the member you would like to make an admin.

At the bottom of the page click the 'Edit' button.

Check the 'Make an Administrator' checkbox below the user's name and birthday.

Click 'Save Changes' at the bottom of the page and this user will become an admin. 

Currently, this cannot be undone so please use this feature with caution.