To generate build files for your platform run in a command terminal:
cd Build
cmake -G GENERATOR ..

Valid generators are:
Windows:
"Visual Studio 12 2013 Win64"
"Visual Studio 14 2015 Win64"
"Visual Studio 15 2017 Win64"
Mac:
"Xcode"
Linux: (see note below)
"Unix Makefiles"

Example: cmake -G "Visual Studio 12 2013 Win64" ..

For Linux Only:
On linux, Debug and Release options are generated by cmake and must be specified like so:
cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Release ..
or
cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Debug ..