Today is my frist day of school.
下面表达有点混乱,不知道你的意思.
I was disppointed by my classmates, since they arrived until the school is finished they were talking all the time.
That's really repugnanted me, especially in my classroom.
I kown what should do, what should't.
In order to changed my life, I must keep to it,(这里的IT是指什么?表达不清.)hang in there until I finish my study.
Then,I sat at the frist row of the classroom.
It's remain me what did together during our summer hoildays.
（它提醒了我暑假一起做的事.It's指什么?together是和谁一起,和你做第一排有什么关系?完全看不懂哪里来的这一句）
We now in different classes.如果说班级,用IN CLASS
I wish both of us can successfully completed our studies .
Come on brother! We certainly will succeed!
Tommrrow belong to the real brave man!I believe in that!
So should you!
在你原文的基础上改的.修正了一些语法.
你应该多看一些外国的小短文.了解外国人写作的习惯.
你的句子的模式还很中国化,外国人可能很难理解.
比如说,最后一句,我坚信,你呢?
外国人不会这么讲,他可能会说,我坚信,你也应该相信!