My father was born in DeKalb County, Georgia in 1948 and adopted through a Florida agency (I think) - not sure if the paperwork is filed in the city of birth or the city where the agency is located. What are the first steps I can take to see what info is available to find info on biological grandparents.

Generally the only options available to anyone NOT a party of the adoption (adoptive parents, birth parents, adoptee) are to register with any information you have on adoption reunion sites.

ISRR and adoption.com are two of the best.

You also have the option of hiring a private investigator, but that will generally get expensive very quickly.

Is there a medical reason for your search, or just curiosity about your biological roots?

You see if parents know the names of the bio parents. What info do they have.

Without any info it is almost impossible to find out anything