Phasing

Well, not being an electrical guy, I am confused.
I watched the MSD video on phasing, thought that I now understood it. Asked another member if I could do it to a Mopar dist and he told me what to do. Just to double check, because I have an FBO ign module set up, I called FBO to ask . The woman didn't know what I was talking about, said she would get back with me.
Today she called back and said that what I was looking at through the hole that I had drilled in an old cap was my vac advance. I didn't know what else to say and said ok and humg up.
So, now I am confused about phasing.