I would walk 500 miles

English is one of the most influential and significant world languages. It's one of the official languages of the United Nations. That's why it's so important to learn it. And it is best of all to start learning English in early childhood.
I've begun I began to learn English when I was four. Of course it that doesn't mean that I learned grammar. In At that age I even didn't know the grammar rules of my native language - Russian. But it was very funny. My teacher was Russian, but she has lived in America for ten years. There were nearly ten kids in my group. We sang simple songs, learned about simple worlds and read children's books, especially fairy tales.
Unfortunately in Russia there are very few children who begin to learn foreign languages before school. And even in schools (usually state schools) pupils begin to learn other languages only in a second class.
For me, school English lessons at school were very boring, because I've I already knew known all the material. I left behind my classmates behind and had a more advanced level than the others. To improve my English level, my mom quickly gave took me to special courses where talented teachers taught us how to speak in English like the people in England speak. That was such a happy and a good time!
After school I didn't practice in English at all. And this is my great mistake. I forgot how to speak and write correctly how to write. I also forgot lots of English words and had to use look up vocabulary. For me it is very important to reestablish and even improve my knowledges. I hope some days that I'll speak English fluently and without vocabulary and confusion.

Quite well-written. You used commas in a lot of situations where they weren't necessary though. Be wary of that.

I would walk 500 miles

English is one of the most influential and significant world languages. It's one of the official languages of the United Nations. That's why it's so important to learn it. And it is always best to start learning English in early childhood.
I began to learn English when I was four. Of course, it doesn't mean that I learned grammar etc. At that age I even didn't know the grammar rules of my native language - Russian. But it was very funny. My teacher was Russian, but she has lived in America for ten years. There were nearly ten kids in my group. We sang simple songs, learned simple worlds and read children's books, especially fairy tales.
Unfortunately, in Russia there are very few children who begin to learn foreign languages before school. And even in schools (usually state schools) pupils begin to learn other languages only in a second class.
For me, school English lessons were very boring, because I already knew all the material. I left behind my classmates behind and had a more advanced level than the others. To improve my English level, my mom quickly gave me to special courses, where talented teachers taught us how to speak in English, like people in England speak. That was such a happy and a good time!
After school I didn't practice in English at all. And this is my great mistake. I forgot how to speak correctly, how to write. I also forgot lots of English words and had to use vocabulary. For me it is very important to reestablish and even improve my knowledge. I hope, some days I'll speak English without vocabulary and confusion.

[Very good. Remember that 'knowledge' is considered uncountable and so is always expressed in the singular.]