Google Site Search Promotions allows website owners and admins to create special results that appear as the first result to a user's search, and define the search terms for triggering those results. Any URL can be promoted – it doesn't need to be specified as an included site or page in your Sites tab.
Just visit “Promotions tab” in Custom Search control panel to manage all your promotions. To create a promotion - decide on queries to trigger a specific promotion, select a title and URL for your promotion, and add optional information, such as description and image thumbnail. The promotion edit pane also shows a preview of your promotion. When you're done, promotions will display in your search results for the queries that match your trigger list. You can test a promotion by issuing one of the trigger queries in the control panel results preview.