nixgl as an overlay

[markDue]

I'm trying to install nixgl with home manager which is a flake, there is no much the directory just home.nix flake.nix flake.lock.
The README says I can use overlays but one line there is confusing I don't know what to put there
I did all the steps in order the last one I don't get it

{
outputs = { nixgl, nixpkgs, ... }:
let
pkgs = import nixpkgs {
system = "x86_64-linux";
overlays = [ nixgl.overlay ];
};
in

You can now reference pkgs.nixgl.nixGLIntel, etc. <<<====================== what am I supposed to put here?

{ }
}

[markDue]

vini1809, the extracted files are not for linux libssp-0.dll, libstdc++-6.dll, msvcp140.dll, and last x86_64-w64-ranlib.exe this a for windows