Formatting - Date Formats
What if you want your dates to show Sunday, 25 December? Simple, select the cell with the date, click Format/Cells/Number/Custom (If you are too lazy just press Ctrl 1 remember?), go to the TYPE text box and type in dddd, dd mmmm but if you want Sunday to appear as Sun the type ddd instead. The same applies to the month.
d = day m = month y = year