Q:

How to get an image 100% in the middle of every single screen in the world

I have a website with some images, and I want them to be in the middle, now on my screen they are in the middle.  Because I've put them there by moving them to one side, when I get my friends to look at it, the image is off to one side. 
On a 13.5" screen it will look to be in the middle. 

A:

This problem can be easily solved with cascading stylesheets (CSS). 
You can centre the image by using CSS to add an automatic margin to your image, and converting it to a block element. 
Adding this CSS to your page will add an auto margin to the left and right of your minecraft image. 
#minecraft2 {
    margin: 0 auto;
    display: block;
}

You'll also want to remove the align="absmiddle" and hspace="115" from your existing code. 
Finally you'll also probably want to remove the horizontal scorllbar that can appear in some browsers, which can be done by adding this to your body tag:
body {margin: 0;}

