Measure the length and width of your furniture to make sure that 6 yards is enough fabric. Buy a little more for a larger couch or a little less for a chair.
Make a slipcover for your couch by cutting the fabric in half widthwise, giving you two separate 3-yard lengths.
Lay the fabric with right sides together, matching up the edges on one of the 3-yard sides. Use pins to hold in place.
Sew the two pieces of fabric together, removing the pins as you go. Iron the seam flat.
Test the size of your slipcover by draping it over your furniture and making sure it is about 3 inches longer than the couch or chair. Trim any excess fabric, if necessary.
Fold under the raw edges 1/2 inch all the way around the slipcover and another 1/2 inch to form a hem. Sew all the way around, removing the pins as you sew and leaving a 1-inch opening.
Measure the circumference of your furniture. Cut a piece of elastic 4 inches shorter than that, or sew some elastic together, end to end, until you have enough in length.
Insert a safety pin in one end of the elastic. Attach it to the slipcover just to the side of the opening in the hem. Insert the other safety pin in the other end of the elastic.
Thread the elastic through the hem of the slipcover, using the safety pin as a guide.
Pull the end of the elastic out. Sew the two ends of the elastic together. Sew the opening closed the rest of the way.