Formally:"행복해요" Haengbok haeyo
Informally:
"나 행복해" Na haengbok hae
"행복하다" Haengbok hada
The Korean phrase for "belated happy birthday" is "늦었지만 생일 축하해" (neujeotjiman saengil chukahae).
당신 때문에 행복 해요 = because of you I am happy
생일축하합니다
행복 한 결혼 기념일 = happy anniversary
We {I'm a Korean too :)} don't usually say 'Happy' but there is a word for death aniversary. 기일 Gi-Il I hope that answer is what you wanted!
saengil chukha hamnida
"해피 피에스타" (haepi piesuta).
행복 한 교사 하루 = happy teachers day
Happy Valentine's Day in Korean is - 해피 발렌타인데이 (he-pi bal-len-ta-in de-i).
행복 한 결혼 기념일 = happy anniversary
hamida is a lyric in the Korean version of Happy Birthday
Eomeoni-nal or Ŏmŏni-nal