wow, that picture they provided for step #4 isn’t helpful at all. So I imagine you’ve already stitched the dart in a previous step, correct? Looking at the dart on the wrongside of the garment, you’ll see that the center of the dart is just folded fabric. You just need to cut along that dart foldline, stopping 3/4″ from the point (or end) of the dart. Now it should look like dart with a uneven seam allowance as the two sides fall open. Then they just want you to trim each side of excess dart fabric, so that it matches whatever seam allowance they provided with the pattern. Obviously the closer you get to the tip of the dart, it’ll start falling below the seam allowance width so you can stop trimming when you get to that point. They usually do this technique for larger darts as to cut down on the bulk of fabric on the inside of the garment. Does this help?