Get fire ant bait that you can spread with a broadcast spreader. Spread it all over your yard according to the directions. Use indoor fire ant bait in your house. After you see less of them, drench their mounds with boiling water.
You can either hire a professional exterminator or tackle the problem yourself. A good thing to do first is visit a local hardware or home improvement store and look at the many over-the-counter products available that will kill and help repel fire ants.
This works on all ants outside. Find their mound and sprinkle Ant Dust (poison)all over it. Cover this with a garbage can lid to help mark the area and keep dry from rain or dew. After time they will be gone.
First things first, ants do eat leftovers. So keeping your house clean from leftovers could get rid of fire ants. Using insecticide for fire ants could also be also used.