Complex sentence: He first studied drawing Vyborg art-school years 1912-1917 and worked for a while decorative painter in St. Petersburg, but moved to Helsinki in 1920, where studied at the Finnish Art Society drawing school years 1920-1921.
Split into simpler sentences: He first studied drawing at the Vyborg art school from 1912-1917 and worked for a while as a decorative painter in St. Petersburg. He moved to Helsinki in 1920, where he studied at the Finnish Art Society drawing school from 1920-1921.