Every good photographer has a set of tools that he uses to manage & convert his files, correct minor mistakes, enhance the images, and so on. Some programs have more features than others, some are harder to use than others, some are very expensive, and some are free. It can be quite hard to decide which to use.
For example, pretty much everyone has heard of Adobe Photoshop, but not everyone knows that there is a free program called Gimp, which is completely free and offers very similar features. At the same time, both Gimp and Photoshop can be quite hard to use, so perhaps a simpler program is the best choice.
In our collection of free articles that we offer for grown-ups, we have a section on photography tools and processes with a few articles aimed at beginners. Instead of repeating the content of the articles here, it easier to link to them directly:
by Simon James Allanach, edited by Alan Frost
For profiles, see Free Photography Resources