Google Analytics by tags
1) create the tag here https://tagmanager.google.com
2 go to google analytics : https://analytics.google.com/analytics/web then add new flux
3) use https://tagassistant.google.com/ in case you want to test locally

4) link of how to mix all https://stackoverflow.com/questions/26774948/how-can-i-test-google-tag-manager-locally