Simplify the following text for a Grade 6 native English-speaking person.
Original: On June 15 , 2007 , the band began their first official headlining tour in support of The Sufferer & the Witness ; it was a North American tour that lasted throughout the summer months .
Simplified: On June 15 , 2007 , the band started their first big tour in support of The Sufferer & the Witness . It was a North American tour that lasted throughout the summer months .