Please look at the following link, where many people have tried to answer your question: http://www.italki.com/discussion/77678

The difficulty is about when I need to use genitive and so on in a words. Not so easy except somebody teach me well :(

yea )))) what is more difficult to study and understand? thnx for answer!

You mean like "How difficult is for us the russian language?" Yeah it's! but also is a beatiful lang.