they should already be under lights from day one dude... don't know why you wouldn't have them under any. if you went from seed, as soon as you plant it, you put a light over it...that's how it works. Keep your light about 1 foot away, more if it's too hot. don't want to burn your baby.
Your pH is too high. if you are in soil, get it down to about 6.0 to 6.2 that's a good number for soil grow. If hydro, then 5.5 is perfect.
The leaves can turn yellow from a number of reasons. If you are in soil, you may be using a soil that has no nutes in it. If that's the case, then feed your plants with 1/4 strength now. If hydro, do the same, 1/4 strength.
My last piece of advise to you is this: Start doing some reading asap! Search the newbie main page for the "how to" threads and learn!!! Growing is NOT easy. If it was everyone would do it. Hell, a lot of people do grow, but not all of them are successful... And that is usually because of a lack of knowledge. Take some time to read and learn. Figure out what you want to accomplish, set some goals for your grow and figure out how to achieve them... that's the best advice I can give. Trust me, reading the "how to" threads is not boring. It's fun to learn about this great plant that we all love. It's even more fun when you understand what it takes to grow quality smoke, and then do it!!!

I really hope that i didn't waste my time here and that this is not falling on deaf ears... We'll see...
Good luck to you, bro!
-S