How to request a FOIA Report!
Simply contact FCPS and ask if they have a FOIA Form, then submit that along with a formal letter to them requesting the Salaries of the officials -- you may need to list individually, or any other pertinent information you are searching for.
As for HS grades, if it's grades of the officials, those are not Job related in the sense that they were in HS many years prior to employment, and would be out of FCPS control or Responsibility. So you have no Right to that information.
If you're requesting current student's grades other than your children, Forget it. They are Minors and have protection under the Law.
You'll probably want help from an attorney, along with sending copies to the FFX. Co. Board of Supervisors depending on the information that you obtain.