Adding code block to bottom of blog page (Brine Nueva 7.0)

How can I add a sign-up link to the bottom of my blog page, below the blog thumbnail images? I already have the code prepared but am not sure how to inject it into the page. Any help is appreciated.

I use Heather Tovey's plugin for this. It's a paid solution, but works like a charm: https://www.heathertovey.com/product/squarespace-blog-footer-plugin/