Paint.NET allows for easy expansion of features through a plugin system. There are two types of plugins, FileTypes, which extends the types of files Paint.NET can load/save, and effects, which add on additional effects.
Plugins are developed and maintained by the Paint.NET community and not the developer. If you are having issues with a particular plugin, please ask at the forums.
Plugins come in a .DLL format. Some sites may compress these files further in an archive format such as .ZIP or .RAR. Please use the decompression utility of your choice and make sure your plugin is in .DLL format before proceeding.
Before beginning, make sure to quit out of Paint.NET.
Locate the C:\Program Files\Paint.NET\ directory.
If you downloaded a FileType plugin, move your saved .DLL to the \FileTypes\ subdirectory.
If you downloaded an effects plugin, move your saved .DLL to the \Effects\ subdirectory.
Navigate to the plugin you just moved. Right-click on the file, and select Properties.
In the "General" property page, look for an "Unblock" button. If it is there, click it to enable use of the file on your computer. If there is no "Unblock" button, you may skip this step.
Relaunch Paint.NET and enjoy your new plugin!