today’s cameras produce great pictures, but for the web, you want to bring down image size - and at the same time make the necessary corrections.
Most professionals use a software called “Photoshop” for retouching their images.
This is the gold standard. However, it is also quite expensive and it takes a while to learn the most important techniques, let alone master all its functions.
I guess this is the reason why Adobe also produced a version of its program that is more affordable and easier to handle, called “Photoshop Elements”.
There are quite a number of other alternatives however: Personally, I use Paintshop Pro, which has more than enough functions for me and also is quite a bargain compared to Photoshop.
It also consistently scores very well in comparisons with other software.
I sometimes also use PhotoImpact which came as part of my website package.
Quite a good program as well although I feel much more comfortable with Paintshop Pro.
However, if you just start editing pictures and do not have a cost-free software as a bundle, then there also are cost-free alternatives like GIMP (remarkably, you can run it on Windows, MacOS and Unix) and IrfanView (more of an image viewer/database, but has the most important editing options).
All these programs allow you to brush up your pictures, although the names of the functions may differ.
I do not want to go into the specific functions of these programs, there are many very good tutorials on the web.
However, I’ll give a short run-down on the most important steps involved in image correction.