I hate to be a buzzkill friend, but I doubt you're gonna get the grow you want with $15 a week. I'm in no way trying to be a dick, I'm just trying to save you from experiencing what I did at the time. I first started smoking and thought "hey it's a plant so I can just grow it no problem" but I ended up spending $400 that I couldn't afford to spend on a set up that produced about an ounce of buds I didn't even want to smoke.
Growing is so much more than just putting a seed in a dixie cup and watering it. You need to buy good soil/growing medium, you'll need to get your hands on some nutes and of course pots and that's just if you're looking at going outdoors. If you're wanting to do an indoor set up you're looking at a lot more expenses. I spend about 10-15 per clone so when I say $15 isn't a good enough monthly budget I'm in no way exaggerating. I would highly recommend saving that money for now and doing what unlucky said and read a lot. There is a ton of wisdom in all of the stickies here and there are plenty of great books. Might I recommend Ed Rosenthal's book, you can get it on amazon for like 15 bucks and there's a wealth of information in that as well.
Again, I'm not trying to be a douche in any way but a lot of the questions you're asking are quite basic and if you don't know the answers to them you'll likely run into problems in the future that you'll have trouble with as well. I messed up a TON of times before I was able to get a decent harvest and even then the harvest wasn't up to standard, I still have a ton to learn but fortunately I'm able to experiment and research. Get yourself a cheap CFL set up going, do some searches on here or google and you'll find all the info you need to get that going. Don't count on getting a huge harvest, but just use it as a learning experience. Like with many things, once you finish your first attempt, you'll be thinking of all the things you could have done to make it better. If you have such a low budget to go with at the moment I would very highly recommend just doing research first before doing anything. Who knows where you'll be in a few months or a year, you might be at a point in your life where you can invest in a better grow set up than you could have even imagined. And you'll also have that amount of time of research and experience under your belt.
Best of luck to you my man!