Transpernt thing

I want to make to make an object (cloth in particular) simi-transpernt without changing the material if possible.
To have a full picture, I modeled a helmet with a veil at the face place and I want this veil to be able to let you see some of the face.

just add a mix shader with mat on top and transparent node on bottom

happy bl

Thank you so much! Can you break this down from a noob prospective?