Webpage Scaling For Different Screen Sizes

Hi, I'm currently in the process of creating a website portfolio for my graphic design work. I have been working on it through a 27" display and how it looks on that is how I would like it to look. However, when then viewing the page on my laptop there is scroll and the sizing is off. All I'm wanting to do is scale everything on the webpage down for different screen sizes, meaning that on all desktop screens the webpages (ones applicable) are no scroll.

I have code in for no scroll and the removal of the headers and footers. 

I don't do coding so have been copying a pasting code when I need it. But I'm unable to find or understand anything on this topic.

Many thanks, James