Complex sentence: During his teens, he raised his pocket money by compiling music compilations and recording them on cassette tapes and selling them to teachers and fellow schoolmates in his secondary school, and this kept him up to date with what's happening in the music scene.
Split into simpler sentences: During his teens, he raised pocket money by creating music compilations, recording them on cassette tapes and selling them to teachers and fellow schoolmates in his secondary school. This kept him up to date with what was happening in the music scene.