Complex sentence: Prior to joining the WBJB staff, he was a DJ at modern rock radio station WHTG-FM, from 1988 until March 2001, when the station was purchased by Press Communications.
Split into simpler sentences: Prior to joining the WBJB staff, he was a DJ at modern rock radio station WHTG-FM, from 1988 until March 2001. In March 2001, the station was purchased by Press Communications.