Ok so you go into your web browser (I use Chrome, others work similar) select what you want to "appear" on the page and then goto "print" from the File/Action menu (browser dependant) once you get the print box you can select what to print (i specified that only what i had selected was printed) you can change the options on printing graphics/backgrounds and if its portrait/landscape etc.... then the main thing is to change your printer from your local HP/Epson or whatever to a PDF file, normally you will have at least one "PDF Printer" chose this, then click print, you should then get the option to save whats being printed to file.....
Job done!..... now if you don;t have a PDF printer driver then you can download and use something like http://www.bullzip.com/products/pdf/info.php
Hope this helps