Copy the new .fst files into the appropriate locations as below...
To appear in the Harmless internal browser.
FL version: [your install drive letter here]:\Program Files\Image-Line\FL Studio ?\Data\Patches\Plugin presets\Generators\Harmless
Where ? is the version you are using.
VST: [your install drive letter here]:\Program Files\Image-Line\IL Harmless\Presets or wherever you pointed the installer to put the data associated with the plugin. Search your drive for 'IL Harmless' if not sure.
To appear in the FL Studio Browser
Save the presets anywhere the FL Studio Browser can see and then drag the .fst files from the Browser and drop on the Harmless Channel.