There are a couple of methods to extract the arils.  First, remove the stem end. Then make shallow cuts from the stem end down to the bottom, using the section divisions, if they're visible, to guide your slicing. Then pull open the sections and remove the arils. You can place the pomegranate in a bowl of water so the juice doesn't stain your hands or clothing as you remove the seeds. Or you can use the back of a spoon to tap the exterior to encourage the release of the seeds into a bowl.