To introduce Google Tag Manager (GTM) to your application, either use the web blocks, or call the client actions from Google Tag Manager Lib in the Header and Body of your page's layout, whichever is the most convenient for your project.
Do not use both web blocks and client actions together, that would add the required js code twice!
Put your GTM-ID, taken from GTM Dashboard, as the input parameter.
For Head, it should be placed as high in the <head> of the page as possible (e.g. up in the Header placeholder of your page's layout).For Body, immediately after the opening <body> tag (e.g. up in the MainContent placeholder of your page's layout).
Google Analytics Event Tag example
This is just a basic example of how Google Tags can be utilized to obtain usage statistics of your website.
Let's say this is a button on your wegpage and you want to track its clicks.
We give this button a new css class "gtm-button".
You can add a Google Analytics event in Google Tag Manager, for the click of this button.
Then, statistics about the clicks of this button will be visible on Google Analytics dashboard.
To get more info on how to set up Google Tags, please refer to the official documentation (https://support.google.com/tagmanager/answer/6103696?hl=en).