With Adobe Reader installed simply click on a file with the .PDF extension, the file will be loaded automatically by Adobe Reader. Alternatively the shortcut to Adobe Reader is located under the "Start\Programs" directory accessed through your task bar at the bottom of your screen.
Adobe Reader is about the simplest program to use on a PC next to (say) Notepad. As a side note, no you cannot edit Adobe documents you only have Adobe Reader (to edit you need the full Adobe package which you have to buy).
I hope all my problems today are as small and simple to solve as this one!