Complete the preliminary paperwork -- the cover sheet, fee transmittal form and application data sheet. You can find these forms on the USPTO website by clicking the "Patents" tab on the USPTO home page and selecting "Patent Forms" from the drop-down menu. You must supply basic information about yourself, list the type of patent you are applying for, specify your method of fee payment, and state the title of your invention.
Create a written description of your invention that includes text, drawings and graphic materials, as necessary. Your description must be comprehensive and precise enough to allow a skilled technician in the field to which your invention is related to make and use the invention himself.
Convert all your documents to PDF files for online filing. This is not necessary if you file by postal mail.
Calculate your filing fee by referring to the fee transmittal form. The filing fee varies according to several factors. At the time of publication, the fee is $190 for a utility patent application, if the applicant qualifies as a "small entity." An individual qualifies as a small entity if he has not licensed or sold rights to the invention. A company qualifies by the same standard if it employs no more than 500 people. A nonprofit organization may qualify if it meets state or national legal standards for nonprofit status and has not licensed or sold any patent rights. You may pay the fee online by credit or debit card. The fee for a postal mail application may be paid with a certified check or money order made out to the USPTO.
Submit the foregoing documentation, together with the filing fee, online by clicking the "Patents" tab on the homepage of USPTO's website and following the on-screen prompts. If you are filing a postal mail application, mail the application package to the Commissioner for Patents, P.O. Box 1450, Alexandria, VA 22313-1450. The USPTO will assign you a filing date and application tracking number.