So I am American and was born in Atlanta, GA... my father during my birth was French Citizen living in America... After I was born he registered my birth with France (so he says). Going off the website of the French Government, they say you are French if one of your parents was french at the MOMENT you were born. And my father was French the moment I was born and only had a green card (for USA). So since he registered my birth, what do I do now to get my citizenship? am i already a citizen when he registered it? or what? can i now get my French passport? Do i need to send in documents or anything to the French Embassy/ Consulate? I CANNOT find ANY information online on what the heck I have to do since I am registered. Can I call someone to check and see if I was registered with France when I was born to make sure of it?
So since he registered my birth, what do I do now to get my citizenship?
Probably nothing, from what you've told us, perhaps unless you're over 50. (There's a fifty-year rule that I don't understand very well.)
Am i already a citizen when he registered it? or what? can i now get my French passport?
Yes. You're probably a French citizen and you can apply for a passport.
Do i need to send in documents or anything to the French Embassy/ Consulate?
Of course. Passport applications always require documents. The link for the relevant page in English yields a 404 error, but there's plenty of information in French including a list of the documents required for a first passport application when the applicant is an adult.