The two girls skipped happily through a field of flowers.
A good sentence using happily is: Sam happily performed on the stage at her school.
Phillip hugged the monster happily.
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
One example sentence using "its" is: "The dog wagged its tail happily."
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.
No, there is no preposition in the sentence "The horse munched his hay happily." The sentence consists of a subject ("the horse"), a verb ("munched"), a direct object ("his hay"), and an adverb ("happily") that describes how the action is performed, but it does not include any prepositions.
You can be going along quite happily, then bing; it does a U-turn.