How exactly do I record an option or sales agreement with the county?

[David Perez]

How exactly do I record an option or sales agreement with the county? My understanding is that this needs to be done to protect my interest should the seller decide to sell the property to someone else after s/he has agreed to sell the property to me. Do I get the contract notarized than go down to the county court house or can I just take the signed agreement as is and file it that way? I’m in Chicago. If this is something that is not necessary please let me know.