Making Custom Brushes

Any image can be turned into a custom brush, but generally, you only want to use images that you'd like to use often in different colours,
gradients, patterns etc.  You can open a .jpg, .gif, .pspimage or .tub file - the only restriction is that they
must be one layer only. You can use text - a poem, quote or just sayings that you might add to various backgrounds.
You can format it with shadowing and/or beveling and make it into a custom brush. The images don't have to be on a transparent background,
but if they're not, the brush will be created in the canvas size, not the image size.

Colour images can be used but most custom brushes are grayscale, because they'll pick up the colours you choose to use more accurately.
Most brushes have a lot of variance in the depth of gray and when you use them with a different colour,
the shading is kept intact.

If you have a colour image you'd like to make into a custom brush and want to change it to grayscale, it's very simple.
I'm going to use this little train gif for example. It's already transparent so I've opened it in PSP, right-clicked on the layer palette 
and promoted the background so that I can use the colourization effects on it.

First I change to a black & white image as below:

Now I want to lighten it a bit, so that there's more of a grayscale effect and variance in the shading.

When you're happy with the result, you export to custom brush

name the image

It's now ready to use - just open your canvas, click on brushes and select the image from the brush tip drop-down box.

Because the original image was transparent, there's a lot of transparency in the brush tip, so I've added a white background layer and used a couple of different colours, a gradient and a pattern to show how the brushes can be used. I've given them a bit of shadow to bring out the detail.