First of all, what a wonderful drawing you have created.  I commend and congratulate you for your fine artistic talent.

Corrections in red.  Stylistics in blue.

Drawing

I promised to post a picture I have drawn by my self. Well, here it is, and a short story too, of course. )))
When I was a little boy I liked drawing very much. I attended a hobby group at an elementary school. I dropped it out after one event.
Once there was a drawing competition held at our school. I had not prepared a picture for this competition. So I thought I wasn't competing. Can you imagine my shock when they called me out at the award ceremony?! I was given prizes [1] for the 3rd and the 4th place, and two little drawings which I was seeing for the first time in my life. It turned out that my teacher had drawn these pictures and put them up for the contest on my behalf! I don't know why she did that. But I was so ashamed that I was given prizes I hadn't earned. So I dropped it out and went in for sports.
Once upon a time several years later, I received two high kicks to my head during a training. A couple of weeks later, I noticed that I was starting to forget words, names, and dates. Sometimes I even forgot my own name for few seconds! It was scary. I was studying at university at that time, so I must say, hard days came. Well, I had to drop out of the sports section. But I didn't only start to forget everything -- I began to draw again!))) To be truthful/To be honest, I was drawing all the time before the accident (at school, at university), but it was not serious. Usually I just spoiled the last page of my exercise books with cartoons. But this time I wanted to learn drawing like a real artist.
I attended evening courses at a local art school for three years. Why did I stop? There were several reasons: I didn't have enough time or enough money. And one more reason (the real one):  I tired of my teacher's correcting my work. He tried not to correct too many of our drawings, but sometimes he got so involved that he couldn't stop already. ))) He had corrected my drawing of a man's foot so much, that I couldn't recognize it anymore. It was too much for me. I decided to take a break for a few lessons, but my work didn't permit my going back. [Variant:  didn't permit me to go back.] [2] It's a pity. (((
So, now you can see my best work up to the present time. It took me a couple of months to draw this picture. The teacher always told me to correct it here and there. But he didn't help me, and I'm grateful to him for that, because I can say, "That's my picture. I drew it by myself".
Thank you for reading this! Please, correct my mistakes.

[1]  It was not clear to me how many prizes you won.  You refer to "a prize" (one), but then you mention 3rd and 4th place, and "two" pictures.  I corrected the sentence on the assumption you won two prizes. 

[2]  "go" is appropriate when the speaker is not in the destination he is talking about.  (I'm in the USA, not in Russia.  So I say, "I would like to go to Russia.")

     "come" is appropriate when the speaker is in the destination he is talking about.  (I'm in the USA, not in Ireland.  So I say, "My friend from Ireland will come to the US next month.")