Complex sentence: During his school years, he received private music and composition lessons, which in his own words, he earned money at the age of twelve at a skittle alley, where he heard the coarse words of the players.
Split into simpler sentences: During his school years, he received private music and composition lessons for which in his own words. He earned the money at the age of twelve at a skittle alley, during which time he heard the coarse words of the players.