From a Home screen, swipe up from the center of the display to access the apps screen.
Navigate:Settings > Users & accounts.
Tap Add account.
If presented, use the current security unlock method (PIN, password, fingerprint, etc.).
Enter the Gmail address then tap Next (lower-right).
Enter the Password then tap Next.
If preferred, tap Back up data to your device's apps, app data, settings and Wi-Fi passwords to enable then tap Next:
Enabled when a check mark is present.
If presented 'Set up payment info', tap Remind me later then tap Next.
To set up payment info after adding a Google account: