Dear Diary,
I was selected as a school captain. It was a joyous moment for me.I was very happy,and thanked my school principal for selecting me as a captain. I thought I could be a good captain of my school.I went home and told all that to my mother. She was also very happy.
I shall soon write again.     
                                        Your's best friend,
                                                                     write your name.

we have to write dear dairy????????? is it compulsory??????
ya, you must mention dear diary, it is cumpulsory! if you write a diary, think as you are writing letter to your friend!
but my teacher told we should not wrt