To know why?
The treatment for iron deficiency is iron replacement- that can be in oral form or intravenous form if one can't tolerate iron tablet or does not respond to oral iron.
Most importantly, is actually to know why you have iron deficiency anemia
( GI bleeding? Heavy menses
? Malabsorprtion etc) and to address the main problem. See your md and have further eval to find the cause of your iron deficiency.