Judge by behavior first
The fastest check is simple: does it do what you asked? Click around the preview. Try the obvious things and a couple of weird ones. Most problems show up the moment you actually use the thing, no code-reading required.
When it breaks, describe the symptom
If something doesn't work, you don't have to diagnose it yourself. Tell the AI exactly what happened: "when I click submit, nothing happens" or "the list disappears after I refresh." A clear symptom is usually enough for the AI to find and fix the cause.
If the first fix doesn't land, say what changed and what didn't. You're debugging together, and your job is to be the eyes.
Learn the words as you go
You'll naturally pick up vocabulary: what a function is, what a state is, what an API does. You don't need to study it. Ask the AI to explain any piece in plain language whenever you're curious. Understanding grows from building, not before it.