To get to the interactive text of your textbook you should click at the link INTERACTIVE TEXT - HTML Document. The first page of the document (contents of paper part of the textbook) will appear. Above there is navigation bar (menu) with links to particular categories of the document of the multimedia textbook.
Click at any of the items will show you contents of chosen category hanging together with this category. It is the list of hypertext links. Click at the link in this list will show you the page with relevant text. At the ends of these pages there is partition with the list of links to relevant texts from various categories from the navigation bar.
The whole document is created as web pages. For studying and reading use the same principles as for Internet.