You can place either AD or BC after the year.
AD = Anno Domini (Latin phrase for "in the year of the Lord").
1 AD is considered the year in which Jesus Christ was born.
BC = Before Christ; years before 1 AD.
Example: the current year, 2020, is: 2020 AD.
There is no year zero, neither AD nor BC.
Nowadays CE and BCE are also used.
CE = Common Era, instead of AD
The year 1 CE = The year AD 1 (or 1 AD).
BCE = Before the Common Era, instead of BC
In (US) American English, usually the month of the date comes before the day, then followed by the year.
In (UK) British English, usually the day of the date comes before the month, then followed by the year.