Verify WordPress Website with Google Webmaster Tools
After update the header file, visit your website home page.. This is important.
Leave this website open in your browser and go back to Google Analytics -(hopefully you have left this open in a tab or different window.. if not click back to analytics
and work your way back to the overview screen of your website tracking
click on real-time overview and you should see this screen with one visitor viewing website ( this should be you if you kept your site open in another tab.. if its zero, go back to your site and click a few pages then come back to this Google Analytics Screen
We now know that GA is installed and working so Let's Go to Webmaster Tools