The lighting is different for every show. The designer sets up all the lights and cues during rehearsals on stage, usually during the final week of rehearsals. We now have twin touch screens and software from ETC, and for the bar shows a Jester. We always need people who are happy about climbing a ladder to rig the lights.
Once the designer has set up the lighting, operators only have to press a button when given a cue by the Stage Manager. Easy peasy! We encourage actors and directors to take their turn operating during another show.