^^Yup, get that light closer.

Get an oscillating fan to move fresh air around and strengthen up those stems.

What kind of soil are you using and does it have nutrients (somewhere on the back it will say N-P-K ratio)? Yellowing could be (and mostly likely is) a result of a lack of Nitrogen, which brings us back to the soil question.

For future reference, don't use clear plastic cups to start with, using solid colored or black, or cover up places where the soil and roots are exposed to light on the sides of the cups.

Also, next time transplant into something a little smaller before putting them in those current containers.

Tin foil can be a fire hazard and creates hot spots, get rid of it as it's not helping anything in this case.

You really should start in the Basic Growing section and read all the stickies at the top of each section. http://boards.cannabis.com/basic-gro...-dankness.html is a good place to start, but don't stop there. 99.9% of the information you need is already posted here, but it will take many days, weeks and months of reading and putting it into practice. :thumbsup: We'll be here if you get stuck on the way.

Happy Growing :jointsmile: