As soon as they get pregnant, they will happily let us know.
My father saw his old friend for the first time in a long time and they happily caught up with each other.
Koichi returned safely and the village was filled with joyful voices.
You're so glad, you get glad again. Wow, you're just happily going through life, aren't you? Joyfully accept that gladness into your life!
This word is pretty old, and it's used like a noun with と(して) added to make it an adverb or たる added to make it an adjective. Make sure to check out the context sentences to get more familiar with this classical word.
This word uses on'yomi readings of the kanji you learned... twice! You should be able to read this on your own.