My dear hometown! I miss you!!

I miss my hometown so much now.
I have not been back home for a year since I came to the university.  It's a very long distance between the school and my home.  I guess you can't believe that I need to spend forty hours on this tour journey.
Especially before I go to sleep,  I can't stop to think thinking of the beautiful snow,the mountains,the blue sky......
I miss everything there.  I belong to there.

 Your vocabulary and grammar are good.  Some of your sentences are “correct but not common,” that is, grammatically correct but not the way we commonly speak.   Here is how I would write it.

 I miss my hometown so much (very much) now.

I haven’t been back for a year, ever since I came to the university.

(I haven’t gone back for a year…)

(I haven’t returned for a year…)

It’s a long way from the school to my home.

It’s hard to believe that the trip takes 40 hours.

It’s hard to imagine that I have to spend 40 hours travelling to get there.

Before I go to sleep, I always think about the beautiful snow, the mountains, the blue sky…

I’m always thinking about the beautiful snow, the mountains and the blue sky, especially before I go to sleep.

 I miss everything about the place.  I belong there.

I miss everything about my home.  I belong there.

 I usually say “’very much.”  “So much” seems to be preferred by women.

“Back” is usually used as a verb except in combination with other words (back up, back off...).

 We don’t usually use a preposition with “there” because that word actually means “at that place” or “in that place,” that is, it already has a preposition contained in the meaning.  It’s the same with “here.”

 I would write it this way:

I really miss my hometown.  I haven’t been back there for a year, ever since I started college.  The distance is too great.  It’s a forty hour trip by train.  I think about my home all the time, especially before I go to sleep…the snow capped mountains, the clear, blue sky…..

We leave two blank spaces after a period and one blank space after a comma.

I can appreciate your thoughts.  Although I live in the flat lands and bayous  of southern Louisiana, my favorite spot is the Wind River Range in the Rocky Mountains in the state of Wyoming.  I often see pikas( 鼠兔, 一种短耳野兔

）

there, cousins of the Ili pika of your region.