Wrap it around a href html command.
See below w3 page for how.
For you it looks like an image, see the below example
<a href="LINK TO WHERE YOU WANT IMAGE TO GO WHEN CLLICKED"> <img src="PICTURE LINK" alt="PICTURE NAME" style="width: NUMBERpx; height: NUMBERpx;"> </a>
I gave you the example above. I assume you have some sort of knowledge since you said you created the image via custom content?
Can you give me your URL link.
Go to the above thread, there's a person from Shopify who will do it for you for free, this will save you from doing it yourself, just in case you might stuff something up.