Diane, you are using the free motion foot which is what you need. Make sure you put on a pair of gloves, a pair of garden cotton gloves for ladies, with a ruberize type of palm or maybe the dotted palms will do, but you do need gloves with palms that will hold the fabric taut. Spread your fingers out and around the area of stiching again keeping the fabric taut. At first go slow, and think of pieces of puzzles, might could help if you draw them on scrap paper first, trying not to cross over lines, you can draw or sew the puzzles design large or small. The larger the design the faster the stippling will take and much less thread. If you practice on a 14 by 14 piece of fabric ( three layers in place), using the puzzle design, you will be ready for your quilt. Move the fabric at a consistent speed, not to fast, watch your stiches as you sew, and if your going to fast it will skip stiches, to slow your stiches will be to small. A short time practicing will get you there.
Good luck