Complex sentence: After having reached a new agreement with his manager in end 2007, his musical career formally started when he released his first solo album, titled "dove" in January 2008, and became the best selling album in the first half of the year.
Split into simpler sentences: After having reached a new agreement with his manager in end 2007, his musical career formally started. His first solo album, titled "dove", was released in January 2008, and became the best selling album in the first half of the year.