To sign don’t like, take your strong hand, touching your thumb and middle finger to your chest while the hand is open. Move your hand away from your chest while touching your middle finger (and ring finger) to your thumb, extending your index and pinkie fingers. As your hand continues to move away from your chest, twist your wrist down, extending all your fingers, as if you're dropping a piece of tissue into the trash can.
The look of utter disdain while shaking your head is optional, but fun!
Don’t like is a great sign to teach your baby to help give them some control over their life and surroundings. To teach the don’t like sign, use opportunities where your baby has an unpleasant experience. Trying new foods is a good opportunity. When your baby tastes a new food and spits it out, make the 'don't like' sign. Counter-intuitively, letting her acknowledge and express when she does not like something often makes your baby more open to new experiences.
Signs like don’t like allow baby to express displeasure about something without having to resort to negative behavior such as outbursts or tantrums. Often, just being able to make themselves understood will take some of the edge off their unhappiness about a situation and help them deal with it in a calm, low-stress way.