I'm not sure I understand exactly what you want. If you're wanting to add color to or over an existing black-and-white image, there are a couple ways.

1. Choose the area you want to color. You can do this w/ the magic selector wand, or by using the lasso tool. Then go to Image > Adjustments > Hue/Saturation. Adjust the sliders to get the look you want. You might try clicking on "Colorize" in that same box, too.

2. Create a new shape over the top of the area you want to color. Fill it with a color; adjust the transparency of it until you can see the image showing through the overlay. You may need to readjust the color again then.

Just to clarify: these are two separate options; not two related steps. Hope this helps.

I want to "color" my countertop with my exact granite that I have a photo of. Use the eyedropper or the clone stamper or something to apply my exact granite.

I know I can use the clone stamp - I've done it - but is the lasso tool or the magic wand the only way to "select" the area I want to stamp my granite unto? With the lasso tool, it ends up very very sloppy - no straight lines at all - like a preschooler coloring a picture. Maybe I just don't have a steady enough hand, but I can't imagine a human being actually getting as straight of a line freehand using the lasso tool as a computer could.

I see people on here doing very clean looking backsplashes thaty they imported from pictures people had of a sample board, and they just applied it over the backsplash area (the pattern repeats but you get an idea).

I was hoping there was a way to get cleaner lines to then apply the clone stamp,

I'm not too bad with photoshop but if you posted the image of your kitchen and the materials you have I might be better able to help you with suggested tools in the program. Helps to know what you're working with.

Rene