Patterns are simply repeatable images. Which means they can repear themselves without causing alot of wrong edges.

Example:

Right:


Wrong:



Patterns are usually backgrounds on websites or images, you can find more here.
Patterns aren't too easy to make. You have to know that the picture can be repeatable without any problems like above. Below you will find the two simple ways of making patterns.


Method 1:
This one will be made by drawing little pixels which makes these stripes. This is probably the easiest way.

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

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".

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

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.

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

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 and installing your pattern:

Now to how you use a pattern. Notice how you install and use it here for method 2.
This is also quite easy, first of all choose the paint bucket tool which is under the gradient tool.

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.
Here's the final result.

Method 2:
Start by opening an image of what you want in your patten, it really can be anything.
Make a 100*100px (icon size) of what you want in your pattern based on the image you opened, you can see mine below. I just cropped something random.

Now open a document on 200*200px and paste/open your 100*100 image in the 200*200px document four times on four layers.

Be sure to drag the four layers into each their corner by using the Move tool (click V on your keyboard to activate). .. Just click the layer first and drag the 100*100px icon in an own corner. It should now look something like this:

We have to rotate the layers to make it repeatable now. Let's start with the two ones on the top.
Go Edit >> Transform and start trying different angles etc. I choose to let mine be like this (I just rotated the top right icon horizontal once) try different things here if you want to:

Okay, it's now starting to look more like a pattern. Do the same below with the two ones on the bottom and make it look the same just oposite. Think mirrors. I rotated the bottom lest one vertical and the bottom right one 180°.
Look at my result:

Now install and use the same way as in Method 1. Nice eh ? ... try exploring some with positions and different images and you'll make awesome patterns.

Tips: Resize the 200*200px image to 100*100px (image > image size) .. This is only an option, and it's used by alot of people.