1. Click System Preferences and then Internet Accounts.
2. Click Google.
3. Type in your email address and click NEXT.
4. Type in your password and click NEXT.
5. Authenticate yourself with your mobile phone(2-Factor Authentication).
6. Check the Apps you want to use with Google and click Done.
7. The following Apps are available to use with Google: Mail, Contacts, Calendar, Notes and Messages.