Hiding White in Geometry Map?

in New Users
Hi,
So I'm using geometry maps for the first time, by applying a wet body (texture?) to the geometry map, but even when I apply the texture, the geometry map stays completely white. How do I remove the whiteness (I've tried diffuse strength, but this makes the character darker than what they were originally.
Comments
Do you mean Geometry Shell? You need an opacity map - white where the mesh should show, black where it should be hidden (at least for fine control - you can hide whole groups from the Parameters pane). The map is applied to Opacity on a 3Delight shader, Cutout Opacity for Iray.
Do you have a link to anything on Opacity maps? i've never heard of them before
Here's a picture of what I mean, by the way: