(your address)
3rd november200x
(the name of your boss)
(company name and section work with)
(company’s address)

　　dear (the name of your boss),

　　i regret to inform you that i decided to resign from my present position as (position) with effective from (next day of last date).

　　thank you for giving me a chance to learn and to gain the valuable experience in (company name and section work with). i hope my resignation would not cause you much inconvenience.
thank you for your kind attention and would appreciate if you could let me have a reference letter before i leave.

　　yours faithfully,
(your full name)