1)Open a topic.
2)Do one of the following:
•Right-click in the Design Editor and select Add To > Master Pages.
•Select Output > Master Page > Add Selected Topic To Master Pages
All the content in the topic is wrapped in the body placeholder. After you add a topic to a master page, any new topic created from this master page includes its body placeholder content.
When topics are associated with a master page, the style sheet, header, and footer of the master page override style properties of the topic. You can edit or change the CSS of a topic later.
note: Use the Topic Properties option to change the master page associated with a topic.