how to implement own shaders in forge mod

I've seen a few mods, like alex caves for example, which use shaders in their mod. I've also set up a mod now and put in under assets/shaders a core, post folder, with some shader programms in them. The only thing I'm missing is, how to tell the mod to have those shader active in the background, while playing.

Edited March 8, 20241 yr by BananaPh0ne