If you have never tried using the quilting guide that comes with your walking foot, DON'T, particularly if it is a Janome. Because it only works when you attach it to the right hand side of your walking foot, you can only quilt with the bulk rolled inside the throat (6½/7" on my MC 3500). Just as well it is only a throw quilt for a 3 year old to drag around, and to cuddle up with her 2 cats as the stitching is as straight as a dog's hind leg. Poly batting doesn't help either.
Next one will be wool/cotton batting and NO quilting guide. Talk about learning the hard way, but after she has dragged it around, the cats have slept on it, and it has been washed a few times, it will probably be a case of 'a blind man will be pleased to see it.