1. Because of the boys who are laughing at me, I am steaming.
She is steaming because of that girl.
2. I am frightened by bugs.
My teacher is frightened by ghosts.
3. I am in big trouble now.
You're in big trouble because you are late.
4. I am crazy about stickers.
Why are you crazy about that band?
5. I am doing my best to be good at it.
I know you are doing your best.

Julie: Because of the boys laughing at me, I am steaming.
Correct: Because of the boys who are laughing at me, I am steaming.
Explanation: The pronoun 'who' is used to show which person or group of people you are talking about. You are talking about the boys who are laughing at you.

Julie: Your in big trouble because you are late.
Correct: You're in big trouble because you are late.
Explanation: You're is the short form for 'you are'. 'Your' is a determiner is used to show the relation of the person or people you are talking to.

Julie: Why are you crazy about that Band?
Correct: Why are you crazy about that band?
Explanation: The word 'band' only is not a proper noun so don't capitalize it.

Julie: I know you are doing best.
Correct: I know you are doing your best.
Explanation: 'Your' is used to determine that 'you' is doing best.

Hello Julie! Good job! You really can make sentences on your own. You just have to polish your grammar. Keep learning English!:)