Some larger documents  are presented in Portable Document Format (PDF).  If you do not have it already, you will need to download and install the PDF viewing software.

To download and install Adobe Reader:

Visit the Adobe Reader Web site and follow the instructions to download the appropriate version of Adobe Reader for your operating system.
During installation, Reader may integrate ("plug in") with your Web browser. This will enable it to open automatically whenever you click on a link to a PDF file, and to display that file in your browser window rather than a separate window.