You can find the code in your theme editor. From the screenshot you sent, I’m guessing this might be in a Snippet called image-content.liquid or something similar.
If you change a template file like that the link would apply to all instances of that section. If that’s the only instance that’s fine, but if you have multiple you’re probably better off adding a custom link field to this section so can add a link from the Customize Theme section.
*Assuming there’s no link field in the Customize Theme area, if there is, then you can just paste the link
Thanks Joe. I have added the Image Link into the schema so that I can have separate links for each of my images. However, I need to add the HREF and am unsure how to do this in a way that ensures it utilises the link selected in the Customise Theme.