To apply you need to be three years of permanent resident if you are married to United States citizen or to be permanent resident for five years.
You need to pass a test in history and civics and be able to communicate in the English language. ( if you are a permanent resident for at least 15 years and your are older than 55 years, you may be exempted to take the test.)
You need to demonstrate that you are a person of good moral character.
You need to present your permanent resident card, social security,
Two pictures passport style
Paid $725.00 to the government
How long it will take
It is taken at least 11 months to complete the process to become a naturalized citizen.
You will have two opportunities to pass the citizenship exam, if you fail, then you can submit a new application.