Use the crop tool to select a part of your image and discard the portions outside of it.
Select the area to crop.
With the cursor (it should appear as a crosshair over the image), click and hold inside the picture to select the area you wish to crop down to.
Click the crop icon.
After you have selected the area to crop, click on the crop icon to crop it.
Submit to save.
The cropped image with the new dimensions will be displayed. Click submit to save the image.
