How do I create a custom backsplash?

[Mitch S.]

I am trying to create a custom, 18" backsplash and apparently making it much harder than it needs to be. When finished, I would like to use it in my cabinet specifications. The 18" splash will be comprised of three, six inch rows of tile. Each row will be unique and I have downloaded images from the internet.
I would appreciate any help here as I am new this.
Thanks!