Resolution issue? Webpage different for everyone?

We made new wallpaper, and for some people it looks as planned, but for some people its all different! Its the resolution of the computer.

How do I make it where its the same for everyone, no matter the browsers, or computer resolution?

Well no matter how you do it, it still depends on the computer display and the DPI.

Yes, thats what I thought.

Guess, I need to just do a simple background, so its the same for all.