Short answers, pulled from the story.
The Russian Civil War lasted from 1917 to 1922, sparked by the Bolshevik overthrow of the Russian Provisional Government in October 1917. The war effectively ended with the Red Army's capture of Vladivostok in October 1922, though the final organized White resistance, the Ayano-Maysky District under Anatoly Pepelyayev, did not surrender until June 1923.
There were an estimated seven to twelve million casualties during the Russian Civil War, mostly civilians. The war also contributed to the Russian famine of 1921-1922, which killed about five million more people.
The two largest combatants were the Red Army, fighting to establish a Bolshevik-led socialist state under Vladimir Lenin, and the White movement led principally by Admiral Alexander Kolchak. Other significant forces included Ukrainian anarchists of the Makhnovshchina, Left Socialist-Revolutionaries, non-ideological green armies, and thirteen foreign states that intervened against the Red Army.
The Allied powers intervened primarily to re-establish the Eastern Front of World War I and prevent war materials from falling into German hands. They also feared the spread of communist revolution and the possibility that the Bolsheviks would default on Imperial Russia's foreign debts. Three Central Powers states intervened to retain territory they had gained under the Treaty of Brest-Litovsk.
The Red Terror was a campaign of mass repression that is considered to have begun between the 17th and the 30th of August 1918, triggered by the SR Fanny Kaplan's assassination attempt on Lenin on the 30th of August 1918. More broadly the term applies to Bolshevik political repression throughout the civil war from 1917 to 1922, carried out by the Cheka secret police under Felix Dzerzhinsky.
Kolchak was arrested by the Czechoslovak Legion while traveling to Irkutsk after losing Omsk, and was handed over to a socialist Political Centre. He was shot on the 6th or the 7th of February 1920 along with his prime minister Victor Pepelyaev, and their bodies were pushed through the ice of the frozen Angara River.