Hey, DrPlague…
If you’re brand new to code you will do well to start with basics and learn compiling and such. Once you are confident with that, you may find better answers amongst the FNF community who are likely using the same libraries you are trying to use. I use Haxe lots but the information you provided isn’t enough for me to give guidance other than Haxe can’t find your library. Perhaps the imports on your code page are wrong, or you’re missing a lib in the hxml file.
Looks like there’s a good list of FNF resources here. and there’s a lot of videos on YouTube. Good luck!