Usually, to show possession, you add 's to the end of a word.
the dog's bowl = the bowl belonging to the dog
the cat's tail = the tail belonging to the cat
the book's pages = pages belonging to the book
This is not true for it which can cause confusion. The possessive form of it is its, with no apostrophe, and it means "relating to or belonging to a certain thing, animal, etc."
The dog licked its bowl.
The cat swung its tail in the air.
The book had some of its pages torn out.
It's is a contraction of "it is".
It's [=It is] getting cold outside.
Do you think it's going to snow?
I know it's hard, but I believe you can win.
I hope this helps.