Some patterns are easy to make, and this one I will show you now is especially for you beginners out there.

1. First of all, open a new document on 10*10px.

2. You now got to zoom long into it, to get best possible result.
Click the Zoom tool or click " Z ".
Make sure it is zooming closer and not further away, then click the ( + ) in the left corner of ther window. And mark the "Resize windows to fit".

3. Click the 10*10px window untill you're the closest you'll get.
We will now start drawing the pattern.

4. We will use the Pencil tool to draw the pattern. You find that by rightclicking the Brush tool.


Make sure the size of the pencil diameter is 1px.
You do that by clicking the little arrow pointing down from where it says "Brush" on the toolbar.

5. Now, let's start drawing it. This is not as hard as you think.
Start drawing one px at the time down across the sqare.

And further on..

WOOOO ! You're now over the amazingly hard drawing ! Haha ;P

6. Done soon now. Click Edit > Define Pattern.
A new window will now pop-up where you write a pattern name and click OK.

Yay ! You're now done with the pattern, and adding it. How to use it will come next.

Using your pattern:

Now to how you use a pattern.
This is also quite easy, first of all choose the paint bucket tool which is under the gradient tool.

2. Open a new document on whatever size you want. I use a 100*100px document with a white background just to show you.
Go on the left corner and choose pattern instead of foreground on the paint bucket tool settings.

Beside there, there's a little sqare where you click the little arrow next to. There will now pop up a little menu with all you patterns. Just double click the pattern you made and click / fill the empty 100*100px document.

You are now done !! :D
Awesome job.
Here's the final result.