Step 1: Click to create new trigger
Step 2: Enter trigger name and click on trigger configuration section
Step 3: Choose DOM Ready trigger
Step 4: Save the new trigger
Step 1: Click to create new tag
Step 2: Enter tag name and click on tag configuration section
Step 3: Choose tag type - Custom HTML
Step 3: Add the script to the HTML section and choose our created DOM ready trigger
Step 4: Save the tag
Step 1: Click to submit changes
Step 2: In this step we can see our changes and we can click to publish them
Step 3: Here we can enter Container version name and description and click Continue. Otherwise, if we don't want to enter anything here, we can just click to Skip
Now the script should be added to your website.