How do you say happy birthday in mandarin chinese?

sheng ri kuai le. chinese characters are 生日快乐。 The "e" in sheng生 is pronounced like the "u" in umbrella. So applying english rules you would say shung. The "i" in ri日 is also pronounced the same as the "e" in sheng生。The Word kuai快 would be said "k oo ai". "ai" would then be pronounced like the Word "I." Then the "e" in le了 would be pronounced like the the "e" in sheng生 and the "i" in ri日。 Hope this helps!