Fleas in my home. What do i do?

My son has been severely bitten by fleas. I know it's my fault because the dog showed signs long ago and i did nothing. I thought it was just his normal allergies because he scratches all the time anyway from allergies i already treat him for. I can't afford a professionl job done so i have to work hard and do it myself. I have heard of the boric acid and the 20 mule borax. Do anyone know if this really wks. The flea powder u buy in the store definitely does not wk. I need help fast. Can anyone give me any suggestions.