The following idioms express happiness:
to be over the moon: "He was over the moon when she agreed to marry him."
to be thrilled to bits: "They were thrilled to bits when they won the lottery."
to be in seventh heaven: "I was in seventh heaven when I learned that I was accepted into medical school."
to be on cloud nine: "He is on cloud nine because he is in love."
to jump for joy: "We jumped for joy when we won the game."