Leftovers is all I used. I don't use a recipe because living here in Lafayette LA you were raised on gumbo and learned to make it "by ear." I think I had gumbo in my bottle instead of milk when I was a baby.
Anyway, make a roux or buy some in a jar already made. If you buy the roux, saute the holy trinity; celery, onions and bell pepper, in a pot. After they wilt you can add the roux. All quantities depend on how much you want to make. Add your sausage...let that fry/simmer a while then add water. Too little is better than too much. A touch of tomato can't hurt either. Finally, add the chicken.
That's the basics but there are thousands of recipes on the internet if you want to go step by step.
John Folse is a great Cajun Chef...check out his website for delicious recipes: http://www.jfolse.com/newfindrecipe.htm