I’m not - I am not
Ex - "I'm not used to traveling so much."

You’re not / You aren’t - You are not
Ex - You're not going to that party."

He’s not / He isn’t - He is not
Ex - He’s not my friend.

She’s not / She isn’t - She is not
Ex - She’s not coming for the show.

It’s - It is
Ex - It's just an easy math problem.