What is a watermark? 
A watermark is a type of use for a background image. When you scroll with a background image, it'll usually be in alignment with the text so it's stuck in a position. It'll go upwards when you try scrolling down. With a watermark, the background image usually stays with the screen. So if you scroll down, you'll still see the same pattern, not moved. 
  
How do you make a watermark? 
As you make a watermark, you have to go into "CSS" coding. It's a simple code that can simply restyle your site. 
  
CSS Coding 
Tiled Watermark: 
 
<style>body{background-attachment:fixed;background-image:url("YOURURLGOESHERE");}</style>
 Repeat X-Axis 
<style> body{ background-attachment:fixed; background-image:url("YOURURLGOESHERE"); background-repeat: repeat-x; } </style>
 Repeat Y-Axis 
<style>  body{  background-attachment:fixed;  background-image:url("YOURURLGOESHERE");  background-repeat: repeat-y;  }  </style>
 No Repeat 
<style>  body{  background-attachment:fixed;  background-image:url("YOURURLGOESHERE");  background-repeat: no-repeat;  }  </style>
 Copy paste any of these code and send it between the < head > < /head > code.Then replace YOURURLGOESHERE with your image url. 
The background-repeat thing, it tells how to repeat your url. 
  
Another way to do this without putting the styles between < head > < /head > is creating a .css file 
make it like this: background.css and copy paste all the code and omit < style > < /style >. You can edit background.css all you want without having to manually going through each page to change it! But you still have to put this tag into each page's < head > tags. 
  
 
<link rel="stylesheet" type="text/css" href="/background.css" />
 *Please note that when I do < tag > with the space to avoid problems with the thread.