What would you tell them about the meaning for the following gestures used in the United States?

Consider that you have met someone who has recently arrived in the United States and they ask your help in deciding what certain gestures mean. What would you tell them about the meaning for the following gestures used in the United States?

Fingers crossed

Thumbs up

Thumbs down

Making a round ring (O) with the thumb and index

finder

Pointing directly at some on