Position your cursor where you want to start your crop, which will depend on what you want to cut out of your photo. Left-click and drag to select the area that you want to remain in your photo. If you want to adjust the starting point of your crop, you can hold down the spacebar to move the selected area, then release it to continue drawing your crop square.
Remember the area you are selecting is the part of the photo that will be kept…the rest will be removed. Release the mouse button to finish selecting your crop area. You can now click and drag your crop square to move it, and drag the corners to adjust it. To cancel the crop, hit the “Esc” key on your keyboard.