Make one of the Masters active by double clicking on it. You can now add standard layout elements to the page (objects, guides, frames, etc.)
Now, you can apply the given master to one of your pages. Double click on the page on which you wish to apply the master in the pages window. This makes that page active.
Now right-click on the page in the pages window and select “Apply Master to Pages.”
Select the Master from the drop down list and click “Apply.” Work you have done in your master will now be on the current page.
This process is especially useful as you develop complex layouts that you wish to use frequently in the multi-page document. Similarly, establishing guidelines for specific locations for columns and flowlines is also very helpful.