Steps:

1. Open Adobe Photoshop by clicking on: Start > Programs > Adobe > Photoshop > Photoshop.

2. Load the image to be cropped by clicking on File > Open.

3. In this case, we will be cropping some of the white tiles at the top of the photo. To do so, click on the Rectangular Marquee Tool located on the top left-hand corner of the toolbar.

4. Select the area of the picture that you want to keep (in this case we selected the dog and part of the mat.) To select, move the pointer to a corner of the image, hold the left mouse button down, and drag the marquee. You can re-size your selection as you see fit.

5. Click on the Image menu and select the Crop option.

6. Now the image will be cropped. The final image should look like this: