Don't be scared. Relax, go slowly and you'll be just fine. If you sew slowly, you'll do just fine stitching in the ditch. You don't even need special feet. (I quilt on a machine that's almost 40 years old and only has 1 foot and it works ok.) If you make a mistake, you can always take the stitching out and try again. You could do outline quilting in the middle square.
Have fun and I look forward to seeing pictures of the finished product.