If a teacher or someone gives feedback on your writing, take those comments and criticisms into consideration when you re-write your essay. Ultimately, what you choose to write and put into your essay is up to you; however, if someone give you advice on ways to improve your writing, it typically means that the message you are trying to get across is not as clear as it could be.
Never be afraid to ask for advice or help in your writing and when you do get help, make sure you thank those who are trying to improve your writing and then really think about why they made the critiques they did. Then, come up with ways to improve your writing as a result.
To improve your writing ability ask for writing advice and re-write your essay taking those criticisms to heart. Attempt to fix the writing that caused confusion in your readers.