Сountries that use the Cyrillic alphabet

Slavic languages, also called Slavonic languages, group of Indo-European languages spoken in most of eastern Europe, much of the Balkans, parts of central Europe, and the northern part of Asia. The Slavic languages, spoken by some 315 million people.

They developed out of the dialects of Proto-Slavic. Today there are 12 Slavic languages: Belarusian, Russian, Ukrainian, Czech, Lower Sorbian, Upper Sorbian, Polish, Slovak, Slovenian, Bulgarian, Macedonian, and Serbo-Croatian. The widely accepted division of the Slavic languages into three groups—East, West, and South.

Based on Cyrillic alphabets of the following Slavic languages are built:

Russian (Russian alphabet),
Ukrainian (Ukrainian alphabet),
Belarusian (Belarusian alphabet),
Bulgarian (Bulgarian alphabet),
Serbian (Serbian alphabet),
Macedonian (Macedonian alphabet).

There are not Slavic languages use the Cyrillic:

Kurdish (in the former Soviet Union)
Mongolian
Kazakh
Kyrgyz
Cyrillic was used in Central Asia in all countries. People still know and use Cyrillic.

Map of Indo-European languages

It is very easy to start from free Alphabet course here: Russian Alphabet