usajobs.com
fedbizopps.gov

Most likely you will have to aligned with a company with gov or GSA registered company that wins a specific contract. Get your resume out to some of those companies and do your homework. There is a constant need for DDM instructors within DoS community, SERE is now civilian run & needs instructors, etc... Teaching civilians will not pay the bills unless you're working every weekend with full classes and every veteran who can spell M4 geting out nowadays is trying to make it big as an instructor.