3.You pull the lower lip over the teeth of the lower jaw, if one bites now, the lower lip lies between the teeth of your upper and lower jaw) and you pull the lower lip tightly (similar as when you smile) while your upper lip remains relaxed. To see whether you do it correctly lay forefinger on the lower lip outside about there where your canine teeth are and push a little towards the corner of your mouth. Then let your fingers go and try to keep the lips stretched like that.