mMy dDream lLife

Capitalize titles.

This is the first times i I am tell foring everyone what does(you all) what my dream life would look like.

You all sounds more natural but everyone is ok too. Would is the conditional, so if it was your dream like this is what it would look like.

Honestly, iI'm only 17 years old and iI don't really know what is my dream life would look like , but iI think the life iI'm living is the best life iI have.

Capitalize I when it is on its own or in a contraction like I've/I'm.

I got a bad score ion thean extremely important exam , and theas a result is iI must be study in theat a bad school. However, iI've allways study-ied hard and gotten a lot of good grands indes at this school, and w. When iI came to an articale class to learn something new, iI met a mounlot of good person who taught me a lot, and we were playing. We've been hanging out together at these day.

The bad score was on the paper, so you can see this difference. Also with commas, they should be comma next to the last word then space. For example, like this. Work on making shorter simple sentences as this one was hard to understand.

I feel very respectgrateful and appreciate for everything tohat makde my own todaytoday feel like a dream.

I am not too sure what you meant, so I changed it to, you are very happy with everything today that made it feel like your dream life.

mMy dream life

This is the first times i that I will be tell foring everyone what does my dream life looks like.

Honestly, i'I am only 17 years old and iI don't really know what is my dream life will look like ,but iI think the life i'I’m living is the best life iI have.

I got a bad score in thean extremely important exam ,and the result is ithat I must be study in the bad school.more. However, iI allways study-hard and goet a lot of good grandes in this school, and w. When iI came to a artical class to learn something new, i I met a mount of good person who taught me a lot, and we wer. We playinged together aton these day.s.

I feel very respectful and appreciate for everything to make my ownthankful for everything today.

mMy dDream lLife

Generally, all words in a title are capitalised.

This is the first times i I tell for everyone what does my dream life looks like.

(1) "First time" should be singular, since you're referring only to one instance.
(2) The pronoun "I" is always capitalised.
(3) "What does my dream life look like" is a question phrase, but this sentence is a statement.

Honestly, iI'm only 17 years old and iI don't really know what is my dream life looks like , but iI think the life iI'm living is the best life iI have.

I got a bad score in thean extremely important exam , and the result is i(that) I must be study in thea bad school. However, iI allways study- hard and got a lot of good grandes in this school, and when i came to a articalI went to class to learn something new, iI met a mount ofmany good personople who taught me a lot, and we were playing together at these days.

(1) "An extremely important exam" sounds more natural than "the extremely important exam" here, because this is the first time you're introducing this extremely important exam. That is unless you're referring to a specific exam, in which case you need to specify which exam you're referring to, such as in: "I got a bad score in the extremely important final exam".

(2) "Extreme" is a noun. The adjective you're looking for is "extremely".
(3) No hyphens in "study hard". It is two separate words.
(4) Unless you were writing this while in class, "went" would be more appropriate than "came".
(5) I'm not sure what you meant by "artical class", so I've removed it for now. Perhaps you can clarify in a comment, maybe providing the native text.
(6) I'm assuming that by "a mount of", you meant "many", which is plural. Hence, I have also changed "person" (singular) to "people" (plural).
(7) "A lot" is two words.
(8) "Were playing" is incompatible with "these days". The former is in the past tense, while the latter refers to the present.
(9) "Day" should be plural ("days"), since "these" implies the plural.

I feel very respectgrateful and appreciate for everything tohat makde my owne who I am today.

(1) grateful: feeling or showing appreciation.
(2) The phrase is "appreciate (something)", not "appreciate for (something)".
(3) I took a guess at what you meant to say by "everything to make my own today".