General happiness:
* Happily: This is the most straightforward option.
* Joyfully: Emphasizes a sense of joy and exuberance.
* Cheerfully: Suggests a lighthearted and optimistic happiness.
* Contentedly: Indicates a calm and satisfied happiness.
Specific examples:
* He smiled happily at her.
* She danced joyfully at the party.
* They lived contentedly in their little cottage.
It's important to choose an adverb that best reflects the specific kind of happiness you want to convey.