You can configure buttons and links that navigate to any Visualforce page. These buttons and links are then added to page layouts. Buttons and links are defined on the database object. In the App Setup area, click Create, Objects, and then click the object. Scroll to the Buttons, Links, and Actions area and click the New button.
Custom buttons and links tied to Visualforce pages can be added to the object’s detail page layout or a related list page layout. The detail page layout requires a standard controller. The related list layout requires a standard set controller. Controller extensions can be used with either.