Click here:
http://www.download.com/3120-20_4-0....=gimp&tag=srch
scroll over to the right and click the first download link.
Once you have mastered or gotten a grasp of how to manipulate images in Gimp, THEN you should think about moving up to Photoshop. Jumping into photoshop raw, you'll get frustrated and lost with all the features it contains. Plus, the newer versions of photoshop require greater computer resources/processing power to operate efficiently. Like Santana mentioned earlier, earlier versions of PS (PS6, PS7) can be bought for about $97~$125.