As another person brought to Roll20 by Adam and having done some tinkering around to figure things out, I've discovered a few ways to do what he does. If you drag a PDF to the Map & Background Layer of a Page, it will prompt for which page of the PDF you want to import as an image. After a bit of quick resizing, you can then use the Text option in the Drawing Tools to fill in the various areas. Players will not be able to see the Page unless you move the Players Bookmark to it. Even then, you can control what text is visible to them by putting text you want them to see on the Objects & Tokens layer. Secret information can be kept hidden on the GM Info Overlay. There's more info, including how to split the players between Pages, on the Roll20 Wiki. Hope that helps!