The first thing you want tod o is to determine the problem. Itt's probably the backlight on you screen.
To check this hold you lap top up to a very bright light, but don't allow any glare onto he screen, turn it on, You should see the shadow images of the stuff you computer normally does. If this happens( I'm 90% sure it will) proceed to next step.
Try pressing the brightness adjusting feature of those lamps, this is usually done with some combination of the Fn key and F7 or F8 (you should see a blue light bulb symbol in the corner of one of these keys.) if this doesn't work proceed to next step.
go buy CCFL tubes (there little diode like lights) If you are unsure about taking you laptop apart don't risk this, follow instructions in link to change back lights.
http://www.laptoprepair101.com/laptop/2007/12/09/replace-laptop-backlight-ccfl-lamp/
If this stuff doesn't work, aggghhh who am I kidding. This WILL work.
I assume no responsibility for you messing up your or any one elses laptop while trying to follow these instructions.