I'm CPR trained with many recerts over the years. AEDs do everything for you, you just have to apply the pads in the correct spot (every AED has a visual diagram) and press the big button. They're intentionally designed to be easy to use now.
Also, get CPR certified. Takes an hour or two at most and you could save a life.
To anyone reading this, this is actually what you do in a situation where there are people around. Due to the bystander effect, you have to call out to specific people to do these things.
CPR only works if it's consistent, and you can't stop until EMTs arrive. After you command people to do these, you ask if anyone else is trained in CPR. Not knows. Trained. And then tell them to sit across from you so they can take over if you exhaust yourself. CPR is tough if you do it right, but you're keeping someone from dying.