In March 1917, there sparked a five day riot of 200,000 workers in Petrograd over shortages of bread and fuel. At first the soldiers were ordered to shoot the rioters but later sided with the rioters.
At first Leaders of the Duma made a provisional government (a temporary government) headed by Alexander Kerensky. His decision to continue fighting in the war lost the support of the workers and soldiers. This worsen the conditions in Russia.
The October revolution (which starts November 1917) was when factory workers stormed the Winter Palace in Petrograd calling themselves the Bolshevik Red Guards. They took over government office, arrested the leaders of the provisional government, and overthrew the provisional government.
Within the takeover, Lenin ordered that all farmland be distributed among the peasants and to fighting with Germany, so they signed a treaty with Germany which was humiliating terms for Russia. This sparked the nation to split because some thought that government shouldn't change and that they shouldn't have stopped fighting with Germany.
NEP (New Economic Policy) was Lenin´s temporary way of a small-scale version of capitalism to jump start the economy because of WWI and the Civil War.
When Lenin suffered a stroke in 1922, the two most notable men were Leon Trotsky and Joseph Stalin, were trying to take Lenin´s title. Stalin began his ruthless climb to the head of the government and when Lenin eventually died, Stalin took power, became dictator, and exiled Leon.