Styling the loop – how does it work?

Hello!
I’m trying to learn how to make my own theme. And now I would like to learn how to style the loop.
I would like to make the loop put out all the posts with a image and the name of the post in a grid-like structure. Here is an example of what I would like to do: https://resonate.io/2015/
How do I do this? Anyone that can suggest where to begin to learn this?

Thanks!