To view a PDF file you will need to have Adobe Reader installed. If you don't have a copy of the free Adobe Reader software on your computer (most computers do), you can download one from the Adobe Website.
This piece of free software allows you to read documents in the convenient PDF format. These are files ending in '.pdf' and are common on the internet.
You will find this piece of software useful not only on this website, but many others too. Once you have downloaded and installed it you will be able to view PDF documents simply by clicking on their links. When you do this, your computer should start up the Adobe Reader software automatically.