I've just downloaded client and updated it successfully but when i type my acc and pass it gives me an error like this

http://radikal.ru/F/s39.radikal.ru/i084/0911/bf/37a9d070ef47.jpg.html

Your ISP is blocked, only way is to use a proxy atm

and how to use proxy?

google hotspotshield, download that.. that should do the trick.. however using proxy is bull****.

can't i just turn of firewall or protection?

You can try, but i doubt it will work.. You have to wait until riot fixes it.. but somehow they're giving me the feeling they dont care about EU players.

Ok thanks for your help and do you know approximately how much time will it take to fix it?

There is no ETA im afraid. We'll just have to sit back and wait.. that is if they even want to fix it :P