Mate license

I’m in the casino business for 18 yrs now(table games supervisor). I was an operations specialist in the USN, and want to go offshore as a licensed mate. In the navy I did true wind, true course and speed,radar navigation,chart navigation,depth charts, radar contact true course and speed, help navigate straights of Gibraltar, damage control school, and of course, 2 1/2 yrs sea time.18 yrs is a long time, so i need a refresher course to pick up mate license and look for job as a mate. I live in Bay St Louis, MS, next to Louisiana, and need to know what routes to take to acquire this information for my re-education, whether it be online or facility. Also need to know of financial assistance or grants available, as my GI bill has evidently expired. I would appreciate all guidance… -MICHAEL