How do I get my parents to let me go to a therapist?

How do I get my parents to let me go to a therapist? Hello, I'm in highschool and I stutter, anxiety is the root of it. I really think venting about it will help since I have no body. I'm really depressed because of my stutter, anxiety, grades and friends but I'd prefer not to tell my parents that yet and only tell that it's because of my stutter. Me and my dad already had a little talk about this but I wanna convince them that I need a therapist. How do I do this?