Based on your question it seems you are ready to file. If that’s that case, you have completed the tough parts! When filing, your application should consist of: (1) a detailed description (technically referred to as a specification), (2) a drawing (if applicable), (3) the USPTO Cover Sheet, and (4) the filing fee. The filing fee for a provisional patent application is $65 for a micro-entity, $130 for a small entity, and $260 for a large entity. Take a look at my past post titled “how do I write a good provisional patent application,” which discusses what’s required for a sufficient description and drawing. Massachusetts Institute of Technology (MIT) has a website containing useful links for entrepreneurs like you attempting to file on their own. Lastly, the USPTO provides a helpful and succinct two-page pamphlet for individuals looking to apply for a provisional patent.
You may file online by clicking here. I suggest you check out a step-by-step guide for filing online found on this site. It even provides screenshots of the application in order to literally walk you through the process.
Alternatively, unlike non-provisional utility applications, provisional applications can be filed by mail or hand-delivery without having to pay an additional fee of $400. So if you prefer to apply by mail address your application to: Commissioner for Patents, P.O. Box 1450, Alexandria, VA 22313-1450. About a week after USPTO receives your application electronically or by mail, expect to receive confirmation from them of their receipt. Such communication should also grant you “PATENT PENDING” status.
As most of the posts before me have touched on, if you haven’t reached the point of filing then I would suggest hiring an attorney to assist you with this complex transaction. Remember that a provisional patent application should basically mirror your non-provisional application, making it extremely important for your non-provisional application to be as sound as possible. A lawyer will help you accomplish this.