From Facebook Developer Wiki

Description

Renders an Add to Profile or Add to Info button (depending upon which section attribute you specify) on an application's canvas page. This button allows a user to add either a new condensed profile box to the main profile or a new application info section to the Info tab.

Important: The button appears only if the application has already called profile.setInfo or profile.setFBML and set info for that user. We recommend you call profile.setInfo after the user has entered enough data for your application to be able to make a compelling info section.

If the user already has a condensed profile box or an info section from the application, the button does not appear on that application's canvas page.

Attributes

Required	Name	Type	Description
required	section	Specifies whether to add a condensed profile box to the main profile (profile) or an application info section to the Info tab (info).

Examples