How to make a plugin for Metasound in a blueprint project?

Hi,
I’m currently working on a VR Unreal project (in blueprint) and I’m trying to create new Metasound nodes that I urgently need.
I am a bit lost because I haven’t found any documentation or tutorials that can help me build a plugin in a blueprint project, specifically for Metasound.
Any help would be very much appreciated,
thank you,
Cecilia