The Photoshop clone stamp tool allows you to copy one area of an image and copy it onto another area. In order to practice this, open a photo in Photoshop. To do this, go to file>open, browse to the photo on your computer, select the filename, and click open. Any photo will do for practice, but if you have one that needs some retouching use that one.
Clone Stamp Tool
The clone stamp tool is located on your Photoshop toolbar. If you do not see the toolbar (a vertical set of icons), go to window>tools to bring it up. Click the tool (seen below) to select it. You can always see what a tool is by rolling over it and waiting for the tool name to appear.
Once on the Photoshop clone stamp tool, you can set your brush options (located at the top of the screen). Brush size and shape, opacity, flow and blending modes can all be selected. If you want to copy an exact area you will leave the opacity, flow and blending mode at their default settings and only choose a brush size and shape.
The clouds are being selected with the cursor, which appears as a target.
The clone stamp is such a great tool because it lets you copy from one area of a photo to another using any type of brush. This can be useful for tricks such as covering up blemishes (by copying from another part of skin) or removing trees from a mountain view (by copying parts of the sky over them).
To select the area you want to copy from, move your mouse to the area you want to duplicate and Alt-click (Windows) or Option-click (Mac). The cursor will change to a target. Click the exact spot you want to start copying from.
The clone stamp is being used to here to paint over the trees with clouds.
It's now time to retouch your image. Click and drag over the area you want to replace or correct and you will see the area you selected in step 4 start to "cover" your photo. Play around with different brush settings and try replacing different areas of your photo until you get the hang of it.
NOTE: Remember this tool can also be useful for fixing images other than photographs. You may want to quickly copy an area of an illustration or fix up a background graphic for a website.