If you need a freeware editing tool, try XnView.
It is a file viewer with some basic editing facilities, certainly better than a lot of stuff given away with cameras and scanners. I used to use this exclusively until I could purchase Photoshop Elements 3.0. Xnview has a useful Enhance Detail option which sharpens and generally improves the appearance of your photo (no options, it just does what it does). If that doesn't work out it has a seperate Sharpen function, where you can control the amount (but nothing else). It will get you started for free as it also has crop, colour, hue, light level controls, etc. etc. Pretty basic, but generally useful and it is free! One thing it cannot do is rotate an image very well, I had to use a free program with my scanner to do that.