1. You will need to set up a "New Custom Variable" in GTM and then choose "Custom HTML"
window._mfq = window._mfq || ;
window._mfq.push(["setVariable", "KEY", "VALUE"]);
to the tag like this:
3. After that you have to add a "Trigger".
You can trigger the tag on anything you want, but if for example you want the tag to be set whenever a visitor clicks a specific button, you can do that by clicking inside the "Triggering card" -> and then clicking the "+" sign in the upper right hand corner
Click inside the new "trigger card" that appears and then choose Click > All Elements
Once you've chosen the trigger type you can set it up like this:
to make it trigger on a specific element on your site. In this example you define the element you want the tag to trigger on by its CSS selector.
Finding the CSS Selector:
Finding the selector of an element in Chrome only takes a couple clicks using the built-in Developer Tools.
To find the CSS selector of a page element:
1. Right-click the element in the page and choose "Inspect" - The Developer Tools window will open.
2. In the Elements tab of Developer Tools, right-click the highlighted element and select Copy > Copy selector.
That's it! The selector string is now in your clipboard and you can paste it into your trigger.
4. When you've configured the trigger as shown above please "save" the trigger and the tag - and then click the "submit" button in the top right hand corner.