Malkovsky,
If you want to just do simple adjustments to compensate for exposure, most picture viewing pograms have simple editing features which are easy to use and work quite well.
http://www.irfanview.com/ is a free download, fast, a good viewer, and has basic editing features. Download the program and the plug-in's.
I used it to adjust your underexposed picture posted. See below.
Most don't realize but picture information is digitized for each shot and integrated into the file if you have that feature enabled. re:
IMG_0814.jpg
Make - Canon
Model - Canon PowerShot A560
Orientation - Top left
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
DateTime - 2008:01:29 17:37:39
YCbCrPositioning - Centered
ExifOffset - 186
ExposureTime - 1/8 seconds
FNumber - 2.60
ISOSpeedRatings - 200
ExifVersion - 0220
DateTimeOriginal - 2008:01:28 00:08:55
DateTimeDigitized - 2008:01:28 00:08:55
ComponentsConfiguration - YCbCr
CompressedBitsPerPixel - 3 (bits/pixel)
ShutterSpeedValue - 1/8 seconds
ApertureValue - F 2.59
ExposureBiasValue - 0.00
MaxApertureValue - F 2.59
MeteringMode - Multi-segment
Flash - Not fired, compulsory flash mode
FocalLength - 5.80 mm
UserComment -
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 3072
ExifImageHeight - 2304
InteroperabilityOffset - 3336
FocalPlaneXResolution - 13653.33
FocalPlaneYResolution - 13633.14
FocalPlaneResolutionUnit - Inch
SensingMethod - One-chip color area sensor
FileSource - DSC - Digital still camera
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
DigitalZoomRatio - 1.00 x
SceneCaptureType - Standard
Maker Note (Vendor): -
Macro mode - Normal
Self timer - Off
Quality - Fine
Flash mode - Not fired
Sequence mode - Single or Timer
Focus mode - Single
Image size - Large
Easy shooting mode - Full Auto
Digital zoom - None
Contrast - Normal
Saturation - Normal
Sharpness - Normal
ISO Value - Auto
Metering mode - Evaluative
Focus type - Auto
AF point selected -
Exposure mode - Easy shooting
Focal length - 5800 - 23200 mm (1000 mm)
Flash activity -
Flash details -
Focus mode 2 - Single
White Balance - Auto
Sequence number - 0
Flash bias - 0.00 EV
Subject Distance - 40
Image Type - IMG:PowerShot A560 JPEG
Firmware Version - Firmware Version 1.00
Image Number - 1000814
Owner Name -
Thumbnail: -
Compression - 6 (JPG)
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
JpegIFOffset - 3484
JpegIFByteCount - 4676
Click on thumbnails to expand image to full size: