Use Gallery to show my pages instead of blog

Hi folks. I’m making a new website and I’m using again minimatica theme, hahaha.
The website is http://www.negen.es.
I’m going to have just pages so I need to show them at main page but I don’t know how. I need your help.

I take this topic as well to ask something else. I need to change all the black backgrounds from black to blue. I mean black one under the gallery and black one under the title pages.

Thank so much in advance.