Storing Directory Folder Names Into Array Powershell

Here's another option using a pipeline:

$arr = Get-ChildItem \\QNAP\wpbackup | 
       Where-Object {$_.PSIsContainer} | 
       Foreach-Object {$_.Name}

For completeness, and readability:

This get all files in "somefolder" starting with 'F' to an array.

$FileNames = Get-ChildItem -Path '.\somefolder\' -Name 'F*' -File

This gets all directories of current directory:

$FileNames = Get-ChildItem -Path '.\' -Directory

$array = (dir *.txt).FullName

$array is now a list of paths for all text files in the directory.