If you wish to alter or create new textures/sprites/tiles/art for blood you need to work within bloods color range which brings the need for a palette file to use in your prefered graphic editor
I have put together this collection of palette files for different programs such as paintshop,adobe photoshop,gimp and others
Download:
http://www.mediafire.com/?558bjbdmr5ppx5d
or
http://www.megaupload.com/?d=AWA5ZX5U
You now need help putting your newly made textures ingame? take a look here
viewtopic.php?f=17&t=1723