A good sentence using happily is:
Sam happily performed on the stage at her school.
The spaniel gnawed happily on a bone.
The family happily reunited with their found dog.
He happily walked through the park.
Yes, the word happily is an adverb.An example sentence is: "I will happily drink all the tea".Another example sentence is: "the couple happily danced the night away".
the prince and princess fell in love happily ever after
I happily ran up the stairs and turned on my DS
She twirled around the room happily, enjoying the music and the company of her friends.
She happily skipped off to join her friends. The story ended happily for the trio.
There is no adjective in that sentence.
The two girls skipped happily through a field of flowers.
And so, surrounded by love and kindness, the little princess lived happily ever after.
You can be going along quite happily, then bing; it does a U-turn.