1
I had a good dream.
Point to yourself for 'I', sign 'good' by moving your hand from your chin to your other hand, and then sign 'dream' by pulling your wiggling 'X' handshape up and away from your forehead.
2
Did you dream last night?
Sign 'past night', point to the person for 'you', and sign 'dream' with your dominant hand wiggling away from your head. Remember to keep your eyebrows raised to indicate a yes/no question.
3
Stop daydreaming!
Sign 'stop' by bringing one hand down sharply onto the palm of the other, then sign 'dream' using the bent index finger moving away from your forehead. You can gaze off into the distance to emphasize the daydreaming aspect.