Trying to find material briefcases and manage existing materials

I have been trying to work with materials and when looking at the help there is supposed to be some briefcases with pre-made materials that you can import into 3DExperience and then access to work with, but I can't find these briefcases.

I also tried to create some materials, but I can't seem to find how to manage them, yet even delete some of the materials I tried to create.

Thanks!