Installing the banner script
Start by logging in to your Google Tagmanager Account and choose the specific website you want to add out banner-script to.
Click on ADD A NEW TAG
Click on TAG CONFIGURATION
Choose Custom HTML TAG
Insert the script in the HTML-window as shown below, and then make sure you check the box: support document.write (This is to make sure that our data-culture attribute does not get deleted by GTM, when use multi-language sites).
Afterward, you need to set up a trigger for the script. Click on TRIGGERING
Choose GTM's premade trigger, as shown below: ALL PAGES (the script will then be injected by GTM on all pages).
If this trigger does not show on you GTM dashboard, then you will have to add it, by clicking the PLUS-SIGN in the top-right corner.
You can now SAVE your new tag.
Name your new tag accordingly for later use.
REMEMBER to submit your work before you can see the changes.