As mentioned in the video, installing the Google Analytics tag on your site or app is absolutely necessary in order to begin collecting and sending data to your analysis tool.
There are two ways to install this tag on your website:
1) You can use a tool like Google Tag Manager
2) You can place the tag directly in your HTML source code (in its <Header> section)
I strongly recommend checking out Google’s information sheet to become more familiar with Google Tag Manager. This tool is free and will help you to easily add multiple tags.
If you don’t want to use Google Tag Manager, you can place this code directly in your HTML. To do this, you can:
Ask a backend developer for help
Use a plug-in from your CMS (like Wordpress) to make it easier
Place it directly in the source code