1. Create a new File measuring 500x500 px with a white background.

2. Obviously you can make brushes with anything! For this tutorial I am going to make a simple design using some of my own brushes. Of course you can make brushes with anything - if its an image with a plain background that helps lots! Here is the image i'll use, you can copy and paste it if that helps you.

3. Now to turn this into a brush follow these simple steps; File > Export > Custom Brush... Then you will see this:

4. You can name it whatever you like, for the sake of this tutorial I named it 'Tutorial'. When creating your own orignal brushes you can put your name in the 'Author' & 'Copyright' boxes.
5. Your new brush will now appear in the brushes folder and will be available to use in your designs! :)