This article assumes you are familiar with Google Tag Manger, if you are not, then please read the official Google Tag Manager Overview article. I'll wait here.
Right, welcome back - from this point forward I'll refer to Google Tag Manager as GTM. So as you now know, GTM sets out to do away with the 'old way' of adding code snippets to your store. Rather than add each snippet manually, you insert the GTM snippet once, and from that point forward, you manage all your code snippets, or 'tags', from the GTM admin section.
SupaDupa allows you to easily insert your GTM container code. To do so, grab your GTM container ID from the top right of the admin section for container:
And paste it into the Google Tag Manager ID field of your SupaDupa store Shop settings:
Hit Save Changes, and you're done! From here on, you can add all other tag snippets directly via the GTM.
How does this affect my Google Analytics code?
Google Tag Manager is simply a container that allows you to load in code snippets (or 'tags'). As such, you should be able to use both the GTM, and the Google Analytics code configured via your Shop Settings for your SupaDupa store without problems. That said, as Google recommends, if you are to use the GTM for your store - we'd recommend leaving the Google Analytics code blank in your SupaDupa shop settings - and using GTM to serve your Google Analytics code intead. See the Install Google Analytics via Google Tag Manager article for a step-by-step on this.