deteriorating yellowish leaves

I read through the forum a little and first of all I want to say hello. This seems like a place I can get to like.

We are growing an indoor plant. SHE has been growing for two or three weeks I'd say. This is our first plant.

USING TO GROW: We are using some sort of plant light. it is about 10 inches away from the actual plant. Im trying to do a sort of green house effect. I have a soda bottle cut on the bottom and i leave saran wrap on the top. We are using Miracle-Gro soil (even though i was told not to). We are using Miracle-Gro All purpose plant food. 12-4-8 I couldnt find anything else at home depot. We use about a tablespoon in a 25 fl oz container but its more like 30fl ozs of water to a tbsp of miracle-gro since we filled the bottle up to the top with water. I use this formula on the plant once or twice a week.

THE PROBLEM: My stem appeared a little yellowish but i thought it was beacuse it wasnt fully mature. After a few days i realized the leaves are deteriorating. Only the bottom leaves. I read around this forum and thought that i was watering it to much and rotting the roots and it was beginning to rot the bottom leaves. So as of yesterday I stopped watering it as much. None of the threads i read discussed deteriorating leaves so i figured I would post some pictures and somebody can help me out.

This is my baby I really wish somebody will be able to offer some good advice.
Thanks a lot :-D

 

Thats all this plant really is, is a test subject.

however for my knowledge so i dont repeat the same mistakes i was wondering what was exactly wrong.

as per what you said.. everything haha. i tried to read up on the internet a bit before i started growing. i couldnt find anything really good until i found this site a few days ago. well i cant say everything i read was bad but it really helps being able to see pictures and this forum offers that a lot more then other sites do. thanks for the advice. However, If i wanted to save this plant so i can get a full growth cycle out of it (for practice purposes only) should i replant in different soil and get a new light? Or will i get that with the current conditions its in?

 

i think the light was too far away. the light i got is a plant light. not sure what sort but a plant light. i will try a better light though. have any specific suggestions on cheaper soil/light.

if somebody could move this to begginer for me. i think its posted in the wrong area :-D

what a noob i am.

oh yeah i originally had the light closer but when i saw the leaves start that nonsense above i thought i was burning the plant and moved the light further away.