Make a test sketch in the IDE. Put whatever you like in it, eg.
// test
Save it. Then find it using Windows. That will tell you where the sketches folder is.
Say you called the sketch "foo". You will have a foo.ino file inside a "foo" folder. The "foo" folder is in the sketches folder. That is where the "libraries" folder goes. (Not inside foo, adjacent to it). Put new libraries into the libraries folder (ie. a directory per library).