Complex sentence: Michael Lardie is an American musician, known for being the rhythm guitarist/keyboardist/backing vocalist of Great White (1986-2000,2006-present), and the keyboardist/backing vocalist of Night Ranger (2003-2007).
Split into simpler sentences: Michael Lardie is an American musician, known for his memberships in Great White and Night Ranger. He is the rhythm guitarist/keyboardist/backing vocalist of Great White (1986-2000,2006-present), and was the keyboardist/backing vocalist of Night Ranger (2003-2007).