It depends what agency. Most agencies have an appellate procedure. All you have to do is go to that agency and request an appeal form. If they don't have it, then you can get a paralegal to help you appeal (or a legal savvy friend) because its administrative and anyone including non-lawyers can represent you in an administrative matter. Check you local statutes on the web found primarily on on your state's legislative site (you will have a link to your state code on that site) and check what the rules are if there are any. Chances are that the legal aid society has its own procedure that operates within itself.