I'm trying to make a face mask to make a dimple ... I've extracted the textures using s3pe, but I'm confused on which textures of the face skin I'm supposed to edit to put the dimple on :/ I'm new to this lol

Do you want it to be a face mask, or an actual edit to the skintone? Cos I don't think you'll be able to just edit one of those and slap it on and have it work as a face mask. You can use them for positioning, though. The bottom one, the pinkish one, is probably the easiest to work from. Then look at some existing face masks to see what their DDS textures look like.

I read in another thread that to make a dimple (not necassairly a face mask) you had to use a face skintone in order to do it. But it seems this person has no idea what they were talking about :/

I was just wanting to use the skin to see if the position was right ... the CTU wasn't giving me any of the base textures to work with for some reason, so I thought sim3e would do the same thing. I guess I was wrong ... and I have no idea where to start without the base texture to work with.

No, no, the face skin is fine for positioning - but then from there you need to make your texture and alpha such that it will look right on the face. If you open up the textures of any other face masks (I know there are nose masks and mouth corners out there) then you should see how they've set up their textures and can do something similar for your dimples.

HP is right, you can use those faces, however, what you should do, in layman's terms, is make the edits on a separate layer in your graphics program, and then delete the layer with the face on it. Then desaturize and lighten the layer with the dimple, and use it to make a makeup face overlay, costume makeup or blush probably.