1. Go to the Dashboard and select one of the two options:

 

2. Copy the Synchronous version of the tracking code:

 

3. Go into your WordPress Dashboard on the “Appearance” tab and click on “Editor”:

 

Editor WordPress

 

4. In the list of Templates, search for the one with the description of “header.php”, select it and paste the tracking code right after the opening of the <head> tag:

 

 

5. Click on Update file and wait 10 minutes in order for the information to be processed:

 

Update file