Understand the duties of notary publics.
When you need an agent who can certify documents, you find a notary public. They are authorized to do this by the state they live in, and they have an official seal. You may need to prove your identity, and then you will allow the notary public to witness as you sign your contract. A notary may also help you find the correct places to sign and date contracts and applications.
Most of us have had to find a notary at some point. Most of the time we need a contract or application notarized. This may be particularly true if you complete your paperwork outside of the place where the paperwork originates. Your signed and notarized documents will be considered official and complete.
If you had to look for a notary, you would probably start your search at your bank, office, or other business. Many companies keep one on staff as a convenience for employees or customers. They may charge you a small fee, and that fee is strictly regulated by the state they work in. Sometimes the service will be free for clients and employees because it is underwritten by the company.