The down and dirty on this:

1.  If you can, make a seamless tile out of your picture.  That way, if people want to use it on sometihng large, they can scale it without having unrealistic seam lines.

2.  Take your seamless tile, duplicate it, make the copy a gray scale image and gaussian blur it a little.  This will be your bump map.

3.  Either save it as two images, or save it as a tif with your bump map saved to the alpha channel.

Could be worse, could be raining.