To activate a button, just click on it. Many of the buttons are explained in the section that follows. The remaining buttons will be described in separate sections. The first three buttons on the button bar control what is shown in the Overview area at the left side of the screen.
Bookmarks are an easy way to navigate within a document.
They act like a table of contents for a document in which you can click on a particular line to bring up that section of the document. Thumbnails are small reproductions of pages through which you can scroll. Clicking on one of the mini-pages takes you directly to that page. In fact, clicking on a particular part of the thumbnail will display that portion on your screen. Another way to get around the text on your screen is to use the Hand tool to push or pull the screen image into position to display the part you want to see.