Sure, it is very easy. I make my own brushes mostly, so I don't have to worry about downloading or crediting, it is such a bother.
To get a brush similar to the one I used on the armour, you need to:
-Take a photo of carpet or concrete.
-Turn it greyscale.
-Shift the levels until you have black spots on white mostly.
-Select area with the selection tool.
-Go edit>define brush preset.
-Name the brush.
-Viola. You have a new brush. You can do this with almost anything, as long as it is in greyscale. You can also fiddle with the brush settings to get different effects.
This is the brush I have:
There are many ways of adding texture of course. This is probably be a bit over the top for your intentions, but you may find a use for it one day. For instance, once I scanned in some jewellery to use as a texture for armour, so it would look detailed.
There are many ways to do things, it is best to just experiment and have fun. Look at lots of tutorials, not so much to copy someone, but to pick up tips and hints that suit the way you work
