happy + for + noun/pronoun
I’m happy for you.

happy + with + noun
I’m happy with the arrangement.

happy + about + noun
I’m not happy about the situation.

happy + to + base form
I’m so happy to see you.

happy + to be + -ing form
I’m happy to be taking part in this event.

happy + -ing form
I’m happy doing what I’m doing.

happy + that + clause
I’m happy that they could come.