you are using a 600 watt bulb to start seedlings?

if this is so, you have your work cut out for you...

if you can, get a compact flurescent bulb from Home depot.. a small cheap bulb and fixture will do.. 10 dollars max.. start your seedling under this bulb.. keep it 5 inches from your soil..

your seed needs to stay moist...all the time.. you can not let it dry out...

if you insist on using the 600watt bulb to start your seedling, you will need to raise it at high as possible and pour 1/8 cup of water on your seed every 6-12 hours..

depending how hot the closet is getting.. regardless, you want to keep the seed and seedling moist for the first couple weeks...

good luck