I have many friends from Post-Soviet countries. Your High school is only for 11 years, in germany it is 12 years. You have to do that one year in Germany in order to get the equivalent of Abitur. Universities like Heidelberg have special colleges, where international students can do that one additional year of studies.
The college is in german, and I do think you can study german there first, and then take the preparation year. For additional infos, I would recommend you to read through the page, and write an email or call to the Studienkolleg - I am sure they will be really happy to help you out!
It might be of course, that you will have to study German first in your home country - I am not sure about that.
Another good site for information is
www.daad.de.