Egg Donation

I would love to be an egg donor! I don't want kids but that doesn't mean I can't give out my eggs to someone who does. I raised my sister and I know that if I do have kids it won't be for a LONG TIME. But I don't know how the process works. Have any of you done it? What's the age requirement? I'm almost 19 but I'm also on birth control can they do it while I'm on it? I'm also a smoker and will have to cut back or quit when the time comes but I knew a woman who smoked and didn't cut back and was able to donate?