Thank you, congthien.
As you told me in your last answer, there are several plugins that can be used for integrate Google codes in the web. I have seen some of them and I think I will find a goog solution for my purpose. First I have to study them, select and try.
I also found a second way to integrate the codes. It is the next. I found it when a I searched for integrate Google Tag Manager code in a web. This second solution is to include the code in the header.php. In order to not modify the original theme file, the good way is to do it using a child theme.
I supose this second solution is also good. In fact, I wouldn’t change the theme files (in the parent theme). But here I have a question: in case a future update of the theme would change the header.php, would I have to work again in the child theme, copying the new header.php and adding again the Google Tag Manager code? I suppose the answer is “YES” (could you confirm that?). And the 2 final questions are: do you ussually change the header.php in new versions or it is a file that normally is not updated instead? In case the file had changed in a new version, how can I know this fact?
Thank you again.
regards,
Vicen?