Corrections in red.  Stylistics and comments in blue.

Talk about Yourself

Hello! My name is Dima. I was born in Moscow, Russia, and I have been living here all my life.

When I was a seven [1] years old, I went to a language school where I began [2] to study Chinese. It’s a very difficult language, so unfortunately I wasn’t able to learn it well enough. I never spoke Chinese after that, and now I remember only a few words.

When I was 15, I entered a technical school, and began to study metrology. It’s the science of industrial measurement and quality control. One of my subjects in that school was information technology and programming. And I literally fell [3] in love with this subject. (At that time, I also fell in love with a girl.[variant: with a certain girl] .. but that [4] is another long story...).

All this/that [5] happened a long time ago. Now I’m an adult, and I’m [6] an IT specialist. My job is to find a ways how to use computers to solve some complicated problems with computers. [7]

[1]  There is a convention, which is not strictly followed, to write out the numbers one through nine in words.

[2] If you say "had begun", it would mean that first you began to study Chinese, and later you went to a language school.

[3]  fall... fell ... fallen   fall in love; fell in love; has fallen in love

      feel...felt... felt       I feel happy.  I felt happy.  Has has felt happy.

[4]  It is so difficult sometimes to choose between the words "this" and "that".  A general "rule" is that if something has just (immediately before) been mentioned, you refer to it as "that".    Person A:  "I fell in love with a girl".  Person B:  "That's wonderful."   (b) Person A:  "I feel sick today."  Person B:  "That's too bad."  Person B uses the word "that", because he is responding to what was said immediately before he spoke.

[5]  You could use use "this" or "that" because you are referring to your entire previous paragraph, and parts that paragraph wasn't written immediately before you wrote "This happened".

[6]  You could delete the word "I'm", and the sentence would still be correct.

[7]  If you put the words "problem with computers" at the end, the sentence is ambiguous.  It could mean that you use computers to solve complicated problems.  Or it could mean that you solve complicated problems that computers themselves have.  I assumed you wanted to say the former.  If you meant the latter, you could say, "My job is to find ways to solve complicated problems in computers."