Yejun: I want to be a Ironman.
Beacuse it can fly.
And it's fast and strong.
I ca go fast anywere.
I want to be Ironman
Correct: I want to be Ironman because he can fly. Also, he can move fast and he's strong. I can go fast anywhere I want. So, I want to be Ironman.
Explanation:
a. You can remove the article "a".
b. Don't begin your sentence with conjunctions.
c. Be careful with the use of pronoun.
d. SO - used at the beginning of a sentence to connect it with something that was said or happened previously
e. Be careful with the spelling.

Hello, Yejun! Thank you so much for submitting your homework. Good job! Please study the corrections that we have in here. Have a good night! Happy weekend! Take care, Yejun! ^^

~ Teacher Belle.