How do I put my mask to the center of my layer

So I have this problem with my mask, becuase when I create a mask, and I want to center it, to be in the center of my shape layer. I can't figure out how to do that, and I tried to contact Adobe Support, been trying plugins and tutorials on YouTube, but nothing on there, was what I was looking for, so I have been told to ask on here, so can somebody help me? I really need this for a animation, but I can't figure anything out. 😞

Please help me.

Easier to understand question:

How do I put my mask in the center of my shape layer in After Effects

All the best

Figuate