Instructions for printing.
For printing Web documents, margins are usually set from the File Menu, in the browser's Page Setup (or Print Options) dialog box. The settings must be big enough to encompass the printer's physical non-printing areas. The values you enter (in inches, cm or mm) are not an accurate reflection of the actual margins. The discrepancy varies between browsers, so set the values by trial and error.
Headers and Footers
By default browsers are set to print a header and footer. The header is usually the title of the page on the left and page x of x on the right. The footer is usually the url (address) on the left and the date on the right. You will want to turn these off.