Sorry Naz, 16 July 2006 was a Sunday so that would be Dies Solis....
...and in the Roman calendar it would be Dies Solis, ante diem XVI Kalends Augusti (if the arithmetic looks a little dodgy, that's the way Romans counted...) ...and they counted their years from the founding of Rome in 753BC, so add 753 to 2006 and so the Roman year should be 2759, or MMDCCLIX.
Back to reality...in Europe (and sometimes in the UK) the normal practice is to write the month in roman numerals leaving the day and year to be written normally. Most people contract 2006 to 06 but I have seen it contracted to just "6".