150-words introductory essay for 6-grader

Hello
I am writing an introductory essay requiring 150 words (actually its an example for my 6-graded cousin). I wanna make sure it's ok... so pls help :)) thanks a lot :))

Dear Sir/Madam
My name is Nguyen Doan Anh Thu and I am from Vietnam. I am in the second semester of grade 9. I'd like to tell you about my background, achievements and goals.

I was born and grew up in Ho Chi Minh city, Vietnam. I go to Tran Dai Nghia school and spent my past four years here. At Tran Dai Nghia, I focus in achieving my goals such as having good results in my classes, acquiring knowledge in English, Biology, Chemistry, which are my favorite subjects.

In my leisure time, I usually play the piano for fun or to relax. Additionally, I enjoy watching movies and reading fictional books. I also do researches on fields such as English or Science since my dream is to be a doctor. This is also the reason why I take part in competitions about these fields, from which I gain achievements and advance in my learning.

Thank you, and I look forward to hearing from you.
Sincerely,
Nguyen Doan Anh Thu.

Hello Nguyen, let me try to help you giving some feedback, corrections, and improvement on your letter.

Dear Sir/Madam(COMMA)
(ENTER)
My name is Nguyen Doan Anh Thu and I am from Vietnam. I am in the second semester of grade 9(9th grade) . I'd(I would) like to tell you about ...

I go(went) to Tran Dai Nghia school and ... At Tran Dai Nghia, I focus(focused)in(on) achieving my goals(COMMA) such as having good results ...

I also do researches on fields(COMMA)such as(like) English or Science(COMMA) since my dream is to be a doctor.
Thank you (in advance for your attention) , and I look forward to hearing from you.
(ENTER)(Your) Sincerely,
Nguyen Doan Anh Thu.

I think you have to pay attention on your punctuation. It is really important to help the readers understand your letter.

I hope this can help you. Good luck! :)

Thanks a lot, Aniani :))

Dear Sir/Madam, in my country I will use Dear Sir/Ma'am
Well, The usage may differ in each country, but the meaning still same:)

I'd like to and I would like to are grammatically correct, but for reading purpose, using would like is better than 'd like
I also do researches research on fields..

and for thank you, i suggest you to give some explanation about what kind of 'thank you'
(i.e. Thank you for reading my simple introduction)