Nee is used when correcting a thought or speech the way Americans say, “bring me one, no, two beers” or if someone says something and you are correcting them. Nein is used if you want something or did something or against an action “I want to go somewhere” Nein!
Ja normally means “yes.” However, when used in the middle of a sentence, the meaning is different. For example, in the sentence Du sprichst ja auch Deutsch, meaning “You speak German, too,” it cannot be translated as “yes.” There is no direct translation. ... meaning “Well of course you would, since you speak German.”
In almost all circumstance, a simple Happy Birthday (Alles Gute zum Geburtstag) works, but if you want to be extra fancy, you can try: Ganz herzliche Glückwünsche zum Geburtstag (All good wishes on your birthday)
Yes or no questions in German are structured by having the verb in first position, meaning it is the first word of the sentence. The verb is followed immediately by the subject (the person or thing 'actioning' the verb). The verb must be conjugated correctly (given the correct personal ending) for the subject.