That is a good clear photo and explanation. As long as the fabric is cut straight and with a uniform seam allowance it will work brilliantly!
This is what I had to do when I was first learning how to use a sewing machine and how to stitch straight, and to stitch even curves!
Put an old needle into the sewing machine, and remove the thread. Then draw straight lines (and curves) on to a piece of paper. Then simply treat the paper as fabric, put it into the machine, put the presser foot down, and "stitch". The holes that the needle makes show you how well you are doing, and it is an excellent way to learn how fast you can sew and still keep it under control!! It is a real confidence builder too as you can see how much you are improving! :-)