Question
please tell me how to get rid of garden ants from my garden

Answer
They usually don't do too much harm. Ants are insects in the Order Hymenoptera, and it should be recognised that they can be beneficial as well as pests. They will kill and eat any insect they find, including fleas, fly larvae and termites. In some areas they are an important part of the natural processes of soil aeration and organic matter breakdown.

Try to tolerate ants outdoors as they are part of the environment and control many pests such as termites, cockroaches, fleas and flies. Increasing the humus levels and using mulch will discourage ants in the garden. Biting ants close to the house, children's play area or gardens may need to be controlled.  If you want to eliminate them organically here are several places to get organic controls:

Boric acid, an organic control for sweet eating ants, or Borax, which is recognized by the EPA as being among the safest and least toxic chemicals available to consumers.

http://www.arbico-organics.com/organic-insecticides.html also carry Terro Ant Bait which consists of a mixture of boric acid and sugar in a liquid solution that attracts sweet-eating ants. Ants carry the bait back to their nest. Terro eliminates the entire colony. Each trap covers approx. 25 sq. ft.

These are available at Planet Natural:
http://www.planetnatural.com has several organic ant controls for fire ants.  

They carry Ascend Fire Ant Bait, a Fire Ant Bait made from a naturally occurring soil fungus (Abamectin), used to eliminate fire ant colonies.  

You could try Safer Fire Ant Bait (Active ingredient: Spinosad), take it back to the mound, and feed it to the entire colony including the queen who dies and the colony dies also.  Terro?Ant Killer is also used for this.

http://www.arbico-organics.com/organic-insecticides.html also carry Terro Ant Bait which consists of a mixture of boric acid and sugar in a liquid solution that attracts sweet-eating ants. Ants carry the bait back to their nest. Terro eliminates the entire colony. Each trap covers approx. 25 sq. ft.

You may have treat the areas several times to control the ants.