it's like 500x better than anything i could write at your age ok
i only really have two things to say which are that you only mention one teenager showing up to taunt the girl, but then at the end you say there are two bodies of the two teenagers that were taunting the girl??? i have a feeling that's a mistake but yeah.
the second thing is that you don't have to describe what the characters are wearing. you can, but the only stories i can think of are usually ones where the clothing choices of a particular character hold relevance to the story. for example, in american psycho, bret easton ellis does often write descriptions of what his characters are wearing, but that's because it's supposed to showcase the way in which the narrator (patrick bateman) thinks as he is the product of an extremely consumerist, materialistic, shallow yuppie culture society, which is the major point of the novel, and the main source of it's satirical qualities.
other than that, you did a really good job (esp for an eleven year old)!