I'm trying to create this site and this is the code I have right now. How do I make a container and place it just like on the "this site"? How do I insert an image instead of  "go to site" button? And make it all responsive just like on "this site"?

That site does it with bootstrap. Not very efficient, but an easy way to lay out elements if you don't know much css. 

Bootstrap though? it's a lot of css just to position a single block. There are easier, lightweight grids. I use skeleton sometimes. or deadsimplegrid

...which is not the answer to your question. Block elements are centred horizontally with

margin-left: auto;
margin-right: auto;

That's the simple answer

Edited January 25, 20188 yr by TimW

flexbox? wait for Mr Smith to come along

Looks like you've done most of the work from your codepen.

As you've set a background-color on the html you need to remove the background-color from the body tag, this will prevent the white background filling the entire width of the container. Then just add a margin-top to push the container away from the top of the page.

Browser inspect tools are your friend :-)