Complex sentence: In 1923, he went to Moscow where he became designer for furnitures in a Workers' Palace, then he created suits and scenes for the "avant-garde" theater of Nikolaï Foregger.
Split into simpler sentences: In 1923, he went to Moscow where he became a furniture designer in a Workers' Palace. Following this, he created suits and scenes for the "avant-garde" theater of Nikolaï Foregger.