Revamp a small company's website

Good morning, I want to revamp my small company's website, https://remtene.it.
Nothing fancy, just a simple five-page showcase site (home; who we are; what we do; contacts; customer area) with no subpages.
The first three pages have a short, simple text; the contact page has a Google map and addresses; the customer page has a forwarding link.
I have some images that I'd like to appear randomly as the website background. Or at least appear in any way, I don't care how.
But I need to be able to upload new images or remove existing ones if I need to.
I also need to be able to easily edit the text on the pages if I need to.