Go to your hysdro store or the hardware store and get a 75w CFL. They look like this. What you want is a bulb that has a spectrum of around 6500k. It will say on the bulb or on the packaging. Use that for now and as you read more and your plant grows you will start to learn what else you need.
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This ^.
go to any store, walmart, kmart, home depot <- the best for growing pot.
that CFL light can be as cheap as 5 or 10 bucks for the little 23w one... that will atleast keep the plant alive. that pic on the right that is linked here, would be the next step up, a large CFL, these can cost up to around 100 bucks for everything (some take a bigger socket called a Goliath socket, larger then the average bulb, keep an eye out for that).
either way, a lot of the smaller ones, or 1 big 85w CFL will get ya going really well. CFLs will work with good results for the entire grow. 6500k (daylight white, bright white) for veg, 2700k (soft / warm white) for flowering <-- youll need that in 1-2 months.
and get some bigger pots while your there. a few of each size, like a 6in diameter one, a 12in... and if your me, an 18in, and a 24in pot.