Invitation

Dear Sir/Madam,

My name is Rustam, and I'm a native Russian speaker from Kazakhstan. I'd like to train work on my English, especially speaking skills. I've got my school (text)book (Russian Grammar, Literature and etc.) and I can help you to study Russian using our school program. If you don't mind, we can practice our skills via Skype. My Skype account is rustam.aisarov. Our local time zone +6 hours Greenwich.

Welcome!

You'll notice I turned all your "I am" "I have" etc. into the contracted forms "I'm" and "I've" for example.  The way you wrote it originally was perfectly correct, and in fact is the better way to write, when you're writing.  The reason I changed them is because you mentioned that your focus is on your speaking skills, so I think it could be good for you to get used to using contracted forms since this is how people speak almost all of the time.  Personally I almost always go with shortforms over the longer forms (ie. didn't > did not) even in formal conversation.

The full forms can however be used in some cases to add emphasis.

I didn't know that. <- this simply states that you didn't know.

I did not know that. <- this states you didn't know, but with more emphasis.  Maybe the new information is very important or surprising to you, and you are kind of stressing the fact that "wow, I just learned something new."