Step One: Start by cutting your fabric into strips of your desired width. The length of the strip should be 2-3x the length of the fabric you are attaching the ruffle to because it is going to lose length when you gather it.
Step Two: Loosen the thread tension on your machine and sew two straight stitches, close together, near one edge of the the fabric strip.
Step Three: Turn the fabric over and find the bobbin threads. Hold onto the bobbin threads as you pull the fabric to gather it.
Step Four: To attach the ruffle to your fabric, simply sew the right sides together. You can pin it in place, removing the pins as you sew.
Now you are prepared to dress up all your home accessories with ruffles!