Or just tell us how you split up the image. I'm not very experienced with image manipulation programs.
This is just a question of knowing the image size, then splitting it with your favorite graphic tool (I used an outdated version of Paint shop pro) - Basically, any tool that has a CROP ability should work. Google will help you find one (Gimp comes to mind for a free one)
Youtube will show you how it is done, should you wish a visual example.
For the Riverbend image, I ended up with 6x files, each being 1350x1100 in size.
RiTz21