How do import the .java code that you get when you open the file in a text editor?

I have been looking all over the forums, and i cant find an answer to this.

i dont know where to copy and paste this:

public bearman class custommodel extends EntityModel {
    

    public custommodel() {
        textureWidth = 16;
        textureHeight = 22;

        
    }

    @Override
    public void render(Entity entity, float f, float f1, float f2, float f3, float f4, float f5) {
        
    }

    public void setRotationAngle(RendererModel modelRenderer, float x, float y, float z) {
        modelRenderer.rotateAngleX = x;
        modelRenderer.rotateAngleY = y;
        modelRenderer.rotateAngleZ = z;
    }
}

thank you for anybody that will help!!!  (: