You would need to fill out form N-400. You can find the form at the following website:
This form may be filed online
The filing fee is $675
Make sure to include the selective service number if applicable and any traffic violation even if paid
Account exactly the travel days and trips you made outside of the U.S.
Do not an answer blank. If not applicable write down N/A
Include your recent income tax return with your application.
Filing and Process
Send the application to the USCIS service center where you reside. The address is listed on the instruction of the N-400.
In many USCIS offices, the citizenship application takes an average of one year to process.
After you file your application, you will receive a receipt notice within few weeks.
Few weeks later, you will receive an appointment notice for the biometrics, fingerprints.
After the fingerprints, within few months, you will receive an interview notice.
In some offices the swear in ceremony is scheduled for the same day and in some offices they ask you to come back for the swear-in ceremony.
In some cases the processing of your application may be delayed due to "security background check." In this case, your case may take several years before is processed. If you are ever in this situation, consult with an immigration attorney to expedite the processing of your application.
Additional resources provided by the author
For a full explanation of the naturalization process, forms, fees, processing times, you can visit USCIS.gov website. It is very helpful.