it kicked the bucket

i was transplanting my plant ( 3.5inches tall) into a 2 gallon planter, i slightly ( accidentally) broke part of the root, i guess it was bad enough to make it just die. i went to bed and woke up and it was just a shrivled up little tiny thing in the bucket. maybe because my light was to close? also just to add this one here i was wondering if a 50 watt blue plant light strong enough to grow with. thank you

my questions:
how do cheaply add humidity to the air around my plant?
is my 50 watt blue plant light to close at 6 inches from the plant?
do i need to be using a lower wattage for the plants stages?(will get pictures when my mom gets home with camera)
and lastly is there just simple ways to growing reagular shcwag, cause this is my first grow and im honestly not expecting like dank ass buds or anything, i just want somethin to cheif on that i didn't have to go buy. thank you

im not using a fertalizer because im using some soil my mom had for her house plants and they lived to be perfectly fine, even to be bright green and luciouse. im not sure why all this stuff comes into play when ditch weed can grow out of the ground with no care whatsoever, ya know?

oh and how would i add humidity to the room without a humidifier? any cheap ways to that? im only 16 so very limited on money