Plugins:
Step one: Find your plugin on the PDN forums
Step two: Download the .ZIP / .DLL to whichever place on your computer (for ZIP save in your PC's download file, for DLL skip to step 4)
Step three: (For ZIP's only) Extract your .ZIP folder. Copy the .DLL file from in there.
Step four: Go to C:\Program Files\Paint.NET\Effects (you should be able to just copy that into explorer and go straight there)
Step five: Paste the .DLL
Step six: Restart PDN!


fonts:
Step one: Find your font on Google or wherever
Step two: Download the .ZIP / .TTF to whichever place on your computer
(for ZIP save in your PC's download file, for TTF skip to step 4)
Step three: (For ZIP's only) Extract your .ZIP folder. Copy the .TTF file from in there.
Step four: Go to C:\Windows\Fonts (you should be able to just copy that into explorer and go straight there)
Step five: Paste the .TTF
Step six: Restart PDN!
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Ues Pictures and i think everyone who has Paint.Net knows this!