Image text block on homepage – how best to create them

Hi

I need to create these blocks of image and text on the homepage of a new site:

https://safehousebrighton.co.uk/images/block.png

The image will be pulled at random from a selection.

I’m scratching my head as to the best way to do this, both in terms of how and where the text is stored (a widget area? custom post?), and how to create a border like that.

If anyone could suggest a good approach that would be great. Maybe a custom post type?

And if anyone can point me in the right direction for how you would build a block like this with CSS that would be great. I can see how the image might be given a border on the top left and right, but that’s about it so far.

Thanks