To tie a plus size wrap dress, start by putting the dress on and securing the waist ties at the front. Next, bring the ties to the back and tie them in a bow or knot, making sure the knot or bow is secure. The key is to ensure that the wrap is snug enough to keep the dress in place but not too tight that it restricts movement. You can also adjust the dress to your desired fit by adjusting the ties at the waist. If the dress is too loose, you can tie the knot or bow tighter, and if the dress is too tight, you can tie the knot or bow looser.