The first thing to do is determine if the picture should be cropped. That is, remove unnecessary areas, usually along the outer edges of the picture, that are just taking up space.

In my example I have drawn a rectangular shape around the image of the saucer to remove some of the extra area that is not needed and is only taking up space and file space. To draw the cropping line just place the cursor into a starting upper or lower corner of the area and click and hold down the left mouse button and start drawing the line. It might take a couple of practice trys to get it right. If you don't like the result and haven't done the crop command yet, just click the mouse button and the crop line will vanish and you can try again. If you did the crop command and don't like the result click on EDIT then UNDO.

If you have the crop line the way you want it click on EDIT then CROP. The area outside of the crop line will be removed.