1. Visit https://www.google.com/recaptcha/ 

2. Click Get reCAPTCHA

3. You will see "Register a new site" form

 A. any label,

B. choose the type of reCAPTCHA V2 - "Validate users with the "I'm not a robot" checkbox

C. Type your domain e.g. myhometheme.net

4. Accept Terms of Service and click "Register"

5. Copy your site key and  secret key

6. Paste into your admin panel