I'm Trying to inset circles on the corner of the mouth but I can't quite figure it out I bought this model for 3d printing and I've been doing some customization to make it look like different characters in the anime. 

Current State of Model: 

Circles I'm talking about: 

Any help would be appreciated, thanks!
I figured it out, I just need to create a cylinder of the right size and position it properly. Then apply a boolean modifier to the mask object with the cylinder as the picked object.