Open the Google Photos app or go to photos.google.com
Sign in with your Google account
Turn on Backup in the app settings
Allow Google Photos to access your photos and videos
Select the backup quality you want
Connect to Wi-Fi if needed
Keep Backup enabled until your photos finish uploading
To save a single photo, open it and choose Upload or Back up
To save photos from your device, move or copy them into a folder that Google Photos backs up
To save photos from a computer, drag and drop them into Google Photos in a browser
Check that the photos appear in your Google Photos library