Originally designed as a simple replacement for Windows Paint, the former student project Paint.NET has since grown into one of the best and most powerful free photo-editing programs around. It offers most of the features you'd expect to see in paid-for software, including layers, levels and curves, and a wealth of effects and filters. Best of all, the program also supports plugins, so if you can't find a particular feature or effect, you may be able to simply download it. There are hundreds of free plugins available to download from http://forums.getpaint.net.and we've hand-picked a few of our favourites here.
Although some plugin packs come with built-in installers, most plugins require you to add them manually. Just browse to C:\Program Files\Paint.NET and copy the plugin's .DLL file to the Effects folder. You'll need to restart Paint.NET before you can access the new features. If you decide you don't like a plugin or it crashes, you can simply delete it from the folder and restart the software.
About Paint.NET and plugins: