Measure the height and width of the stove with a measuring tape.
Cut two sections of 2-inch-wide wood molding 2 inches longer than the height of the stove with a circular saw. Miter one end of each section at a 45-degree angle with a miter saw.
Cut one section of 2-inch-wide molding 4 inches longer than the width of the stove. Miter both ends of the molding at a 45-degree angle.
Place one of the side sections on one side of the stove so that the mitered end is on top -- the angle on the mitered end should slope toward the stove. Using a hammer, nail the molding section to the wall with finishing nails at 4-inch intervals. Repeat this process with the other side section on the opposite side of the stove.
Place the width section on top of the stove against the wall. The mitered ends should fit the mitered ends of the side sections. Nail the section to the wall with finishing nails at 4-inch intervals.
Apply wood filler to the nail heads with a 1/2-inch-wide putty knife. Paint or stain the molding as desired.