Wattage Increase



I'm looking to build my own flashlight. I purchased a 320 lumen halogen bulb from Radio Shack and it requires 12V and 20W. I connected two 9V batteries togeter in series and parrell but the bulb is still not bright. Is there a way to add a special part to increase the wattage. I'm totally new to the flashlight world so i don't really understand much. I think I might have gone wrong buying the halogen lamp instead of a LED but the only LED's Radio Shack offered were low in lumen output. I want to build a beast, if anyone knows of a great place to buy flashlight parts too that would be great. Thank You!