Collect them spread a tarp out dump the nut's on it in a dry area that won't get wet.Let the nut's dry till they are brown and get a old pair shoe's start stepping on the walnut's roll them around with your shoe and some pressure they will come off.
The easy way of doing this so your hands wont get stained is to pick them up from the ground around the tree and place them in an area where you drive your car like a gravel drive way, drive back and forth and let them dry.
