Truthfully I worry about bleach or other chemicals in the paper towel, or the tape root growing too far out, as touching the tape root, or the tiny root hairs can cause problems. But, if your seed is old, or not particularly viable for whatever reason, this method can be a time saver.
The paper towel method is simply placing a white paper towel on a plate, (stay away from colored towels) then you scatter your cannabis seeds on it. Then place another paper towel over the top of them. I have used several paper towels folded up underneath the seed to help hold more moisture. You then moisten the paper towels, and cover with a second plate, or a piece of plastic wrap (to conserve the moisture.) I usually moisten, but not so much there is standing water.
Next place the plate in a warm (70-85 degrees) spot. I like the top of a refrigerator or freezer, as there is a bit of warmth there. You can also use bottom heat, just be careful to not overheat your cannabis seeds. A sunny window can work great too, just again be careful not to over heat the seed.
I recommend checking your seeds every day, and as soon as the outside shell swells and cracks open, and the tap root begins to appear, plant them in your growing medium about 1/4 inch deep. Some growers wait till the tap root is fully emerged, but I recommend planting them as soon as you see the shell crack open.