I usually give an introduction to Scrum first up. Even if the new team member has been working with Scrum before, it's important to create a mutual understanding, as they may have worked in something that called itself Scrum but wasn't.
Then the PO gives an overview about the product and product vision.
Then the Development Team takes over, showing them the ropes introducing them to their working agreements and dev environment.
And then: Pair Programming, pair programming, pair programming. Have the new person pair with each team member throughout the first sprints. It's the easiest way to get to know the team (and vice versa) and the code.
Bear in mind please, that there is no perfect training model here. Scrum doesn't prescribe a certain way of onboarding new team members. This is just my personal experience. Results may vary by context ;)