Complex sentence: They wrote some songs and already were popular among people in school and shows before, at one show, the MTV Lyricist Lounge Show decided to help them out, and introduced them to Lava Records who quickly signed them.
Split into simpler sentences: They wrote some songs and already were popular among people in school and shows. At one of them, the MTV Lyricist Lounge Show decided to help them out, and introduced them to Lava Records who quickly signed them.