To Open File Manager.
File -> Run -> C:\Windows\winfile.exe.
This assumes you installed to the default directory. If not, simply replace C:\Windows with wherever you installed it.
A reason that you may be having difficulty navigating is that progman used small group files to hold and manage each program group. These are no longer installed / added to when using when installing apps/using windows, so there may be no program groups.
But you can create them if you want to.
File -> New
# Personal Program Group
OR
# Common Program Group
