The February Revolution began in Russia in 1917 and was the first of two revolutions to breakout in Russia. The main causes of this revolution was war and the Tsar those two mistakes caused the Russian people to retaliate and demand justice to abdicate the Tsar.
World War I known as the first war was a global war originating in Europe that last from about July 28 1914 to November 11 1918. The main causes of WWI were alliances, imperialism, militarism, and nationalism and those four thing kind of led to the assassination of Archduke Ferdinand.
The Treaty of Brest was basically a peace treaty signed on 3 March 1918 between the new bolshevik government of Russia and the Central Powers that ended Russia's participation in World War 1. The Treaty of Brest was mainly signed to officially end Russia's participation in WWI for the Germans to devote all of their resources to a spring offensive on Western Front.