How do you say happy birthday in japaness?

Question:

my 21st birthday is coming up in september and i want to know what happy brithday is in japaness so can any one help me

Answer:

The others are correct.
If kanji is too difficult for you, then here's just hiragana, it's phoenetic.
おたんじょうびおめでとうございます
In case you don't know any Japanese at all pronounciation wise or anything then it's almost like
Oh-Tah-NN-Joe (Ooh)-Bee-Oh-Meh-Deh-Toe (Ooh)-Go-Zye-Moss
There's a long O after the Jo and after the To.

That's the most formal way of saying it. The ございますand the お on 誕生日 is what makes it so.
If you're more familiar with that person such as a family member or friend then you can just say たんじょうびおめでとう which would be said as Tah-NN-Joe(Ooh)-Bee-Oh-Meh-Deh-To(Ooh)

"Omedetou gozaimasu" is formal and is like saying "Very much congratulations"
Just "omedetou" is more casual and is like saying plain ole' "Congratulations" or perhaps even "Congrats"
"Tanjyoubi" is birthday and "Otanjyoubi" is just a more polite way of saying so.