That wattage is good, just adjust the height to get the temperature you want. For the first week of life the chicks should have a place to go that is 98 degrees. Then you turn it down each week 10 degrees by raising the light until you get down to about 70, which should be during week 4.
You also need to make sure they have a place to get out of the heat. So only put the light over one side of the bin. Add a thermometer so you know for certain the temperature is right.
Also, the chicks will let you know if they are too hot or too cold. Hot chicks will be running around and making a lot of noise, not soft little peeps, but unhappy ones. If they are too cold they will be huddled in a corner and not come out. Keep in mind they huddle a lot anyway, because they sleep a lot, but they wake up often and run around eating, drinking and scratching.