I just noticed a strand of yarn over about three stitches in a couple of places, down about four rows. I need to frog to those mistakes, but goodness, how in the world do I do this? I used my spare needle to try and go under the mistake under one needle. I know I can't just rip out that one needle and make it go down to there. Also, I don't know which way to pick up the stitches. Do I insert needle into the front part of the stitch or the last part of the stitch?