Autism ADHD therapy. Therapy happens?

Hi my son is diagnosed with mild autism lacking social skills. But his IQ is good he is ok in writing reading. But he doesn't smile at others or make friends or respond immediately when asked something.possible ADHD also identified .. he doesn't seems to be paying much attention in class and may look dis engaged. I have approached a behavioral therapist as advised by school and the therapist is taking 45mins session once a week.. therapist is sounding like he's just having interaction with him where he's not sitting continuously but moving around.. I didn't see him guiding my son directly but rather telling me what we need to do. Please clarify how frequently therapies are required to be successful and is this the way therapy happens?