It's been a good day, it's time to go cray-cray My friends all know the right a-words to say
Our phones are blowing up, texting om-nom alert
And we're rolling up the frozen yo-yo-yo-yo-yogurt
We all know the place where you mix your own cup
The cute boys hang there and we all shout "S'up"

Froyo Yolo by Dove Cameron.

Explanation:

Why did you put song lyrics as an English question?

Research some details about 9/11 and make sure you have a solid understanding of everything that happened before you write. Then just start writing your story using everything mentioned in the prompt (complete sentences, enough paragraphs, thoughtful response). I suggest you break it up and plan by paragraph, for example, do a general introduction to 9/11 for the first paragraph, describe the first plane crash in the second paragraph, then the chaos of it in the next paragraph, then the second plane attack in the following paragraph, then the other plane crashes in DC and PA in the following paragraph, then wrap it up with some descriptions on the horror and emotions people felt on that day. Just try to make it original. Hope that helps :)