Step 1: Go grab a pair of 10" channel locks out of your toolbox
Step 2: Pick up rifle
Step 3: Sit down on couch, and perform safety check on said rifle. (Remove magazine, rack charging handle a few times, check chamber to ensure there is NOTHING in it. Lock back bolt, put weapon on safe, repeat three times)
Step 4: While still sitting on the couch, place the butt of the rifle on the floor between your legs, so the barrel is pointing vertically. (preferably a carpeted floor, but if not carpet, get a towel and fold it up to make sure the stock won't slip or scratch the floor)
Step 5: Pick up the channel locks and make sure they are on the smallest setting for the jaw size.
Step 6: Open the pliers up, and place the GRIPS of the pliers on the D-ring, and close the grips so they are resting on and snug on the ring.
Step 7: While keeping the grips closed, push down on the pliers, toward the receiver. This will push the d ring down, thus releasing the hand guard. If they stick, you may need a friend to pull them out for you, or sometimes you can give the rifle a jolt and they will come out.
Step 8: Apply pressure to the d ring in the same fashion, and install the new ones. Maybe with the help of a friend. Make sure they are all lined up and pretty before releasing pressure on the d ring.
Step 9: enjoy your new handguard