Take the leather end of the web sling and poke it through the hole near the butt from the left side . Then place the little metal triangular piece of metal in the slot on the right side of the stock, keeping the pointed end towards the muzzle. Then press the leather tab that is on the end of the sling onto the stud that is on the triangular piece.
The upper part of the sling just bends around the sling swivel, which just snaps into the eyelet that is mounted just below the front sight, on the left side of the rifle.
The buckle is similar to an M1's web sling buckle. You'll have to decide for yourself which side you want banging onto your rifle's receiver.