Complex sentence: In 1965, Vaughan formed his first band, The Chantones, and performed at a local talent contest held at the Hill Theatre in Dallas on June 26,1965, which was his first public performance.
Split into simpler sentences: In 1965, Vaughan formed his first band, The Chantones, and performed at a local talent contest. The contest, held at the Hill Theatre in Dallas on June 26,1965, saw his first public performance.