There were many fronts being fought, the north, south, and east. In Russia there was fighting until the Russian Revolution. In Europe the fighting mostly took place in France through trench warfare. There was also some fighting in North Africa.
Russia was not as industrialized as the other Nations fighting, 2/3 of it's population were peasants, proletariat were exploited, and they had revolutions and changes of governments (Tsar Nicholas II, then Provisional Government, then Lenin who stopped the war).
World War 2 was a world war, meaning it involved most of the countries of the world in some way. The fighting took place in most of the oceans of the world and all throughout Europe, western Asia (aka Russia), northern Africa, and the Pacific islands.
I have the S.S book called World studies Europe and Russia. you will find the answer there i think the answer is. Some ethnic groups were seeking more rights and some more independence because they were living in russia unwillingly.