Come to this site if you want to learn
First they have to get a green card. And they have to be 18 years or older. they also have to been in the U.S.A for at lest 5 years.Or for a short cout you can join the army for at least 1 year.you also have to care for the U.S.A. . You also have to speak english. And you have to pass a civics text . And a interview. And finally you have to say the pleach of allegiance.