first time growing...got some questions

[balls573]

hey this is the first time ive ever grown anything and ive only been smoking for about a month and a half and my brother just decided to germinate about 30 seeds and ive got 10 of them. they are about a week old and right nowthey are about 3 inches tall and have 4 leaves. i have them in my closet with a 48" fluorescant light with 2 40w bulbs how far above the plants should it be? im running it 18 hours on 6 off. the plants all seem to be bent. the first couple days they were planted i just had them in a window and they were growing pretty straight but now they are all bent 1 has died and the the stems of the plants are turning a purplish brown kindof, is that normal or what should i do to fix them? i used regular potting soil from wal mart, should i put anything in it as far as miracle grow i know there are nutrients and other stuff you can put in it do i need any of that stuff and if so what? how often should i water them? i have just been watering them when the soil starts looking dry. when and how can i tell what sex they are? i have 1 piece of white posterboard that i had layin around the house around them but the ends arent covered should the plants be completely surrounded and should i use any kind of ventilation system or a fan? any input would be appreciated i really wantthe 9 that are left to put out alot.
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[IGotTheCottons]

Go to the top of this section, and read the stickies.

http://www.geocities.com/quickgrowguide - or go there.

EDIT: Next time don't make duplicate threads. You posted the same thing in General Indoor, when this one was fine.