HELLO WORLD

Not at all - this is very good, and don't worry, we don't have a bad impression of Russians either. People are basically nice everywhere, even if their governments occasionally do asshole things - and my own country is no more immune to that than yours is.

*="practice" is fine in the US. In the UK, the verb is "practise"

**=But what? Wait! I've just used a c in "practice" again. Aren't I contradicting myself? Well, no because in this sentence it is a noun and the noun always has a "c" on both sides of the Atlantic!

HELLO WORLD

*I think that "you've probably already noticed that" sounds better here 

it was very good in general and the things I corrected are very minute details :)

HELLO WORLD

Don't be offended immediately; not every Russian is so bad. Right now I should be writing a report for a university class, but I am too lazy. :)   (The difference between "to offend" and "to be offended" is one is performed by the subject of a sentence. "They offend me." They are "doing" the offending.  "They are offended by me." Now I am the offender! You used "offend" in the imperative, as a command or plea. What you probably meant was, "Please don't be offended BY me." 

Also, "Right now I have to do THE report for university" implies that you will only have this one report to write forever. "the" is a definite article. You could have said, "that" or "this" report just as explicitly. If you had used "a" report, it would imply that this is just one report of many (which I'm sure there will be, given that you are at university!). And, as many Americans also mistakenly write, "to" for "too." We also have "two" just to make it more interesting. :)  It's the same problem with "there," "they're," and "their." I am studying Italian on italki, DuoLingo, and OneWorldItalian.com. I love Italian because ALL the consonants are pronounced and the rules universally apply. I have a friend who taught Russian and I tried to learn it for awhile, but I was so frustrated at trying to learn a new alphabet. I'm impressed when anyone (like you) tackles a new language with a NEW ALPHABET!

Instead of that, I decided to find some place where I can practice my English.

^Perfect, except I would not have written "Instead of that." I would've written just "Instead." But, yours still works well.

I guess I'm not so bad in English (at least I hope so :)

"I guess I'm not so bad at writing in English" would be clearer.

The number of corrections will show this), but I feel myself some kind of "bounded".

Not sure what you mean by "bounded." Maybe "limited" would be a better word here.

I mean I have quite small lexicon and huge lack of idioms knowledge.

Idioms are the best and worst aspects of any language, in my opinion. English is filled with them. I love idioms in other languages. In Italian, some people say "In bocca al lupo" (in the mouth of the wolf) to mean "Good Luck." In English, if we want to wish someone luck before they go on stage to perform music or acting, we say, "Break a leg." Is there a Russian idiom for wishing someone good fortune?

I always build sentences in the same way (you have already noticed that probably).

I think you have a good variety of sentence structures!

So I want to have a chat with good English speakers for reducing lack of practice.

So, I want to have a chat with good English speakers in order to (idiom!) make up (idiom!) for my lack of practice.

Rereading this, I understand that my grammar sucks too XD

Your grammar doesn't suck at all. ("suck" is an idiom! And it's a little vulgar, so you need to be careful about when you use it. Here's an article about "suck" and how it should be part of our lexicon. http://www.slate.com/articles/life/the_good_word/2006/08/suck_it_up.html

Very nice job. Now get back to writing that paper!! (I'm a retired school teacher. :) )

Paul

HELLO WORLD

Я бы не стал писать  "(don't offend immediately, not every russian is so bad)" 

Я тоже могу ошибаться в грамматике поскольку English my second language.  К сожалению, желающих изучать Русский среди Американцев меньше чем желаюших изучать Англиский среди Русских поэтому у нас с тобой слишком много конкурентов и трудно найти партнера по языку.