Use the preposition in:
1.with the names of the months:
Ex: I was born in June.
2.when you speak about years:
Ex: My mother was born in 1961.
Ex: We start our school in autumn.
4. period of the day:
Ex. My brother watches TV in the evening.
Use preposition on:
1. days of the week:
Ex: I go to sport club on Friday.
Ex: We celebrate Christmas on the 31st of December.
Use preposition at:
Ex:I get up at 7 o'clock.