Complex sentence: Yelle then began working on and recording their debut album, "Pop Up", in 2006 while performing at night, producer Tepr had been roped into the band in 2007 after meeting GrandMarnier while working as a journalist.
Split into simpler sentences: Yelle then began working on and recording their debut album, "Pop Up", in 2006. While performing at night, producer Tepr had been roped into the band in 2007 after meeting GrandMarnier while working as a journalist.