After much research and many missteps, I got a shared folder to work. This procedure is for a PCLOS guest on a Windows host.
Guest additions must be installed.
To access a Windows folder:
Create a folder in Windows to access (does not need to be shared). For this example let's use C:/Users/User/linux
Create a share point in Vbox using shared folders for PCLOS guest i.e. C:/Users/User/linux. (The name will be linux in this example)
Create a mount point in guest's home folder i.e. /home/yourusername/Windows
As root, put this line in /etc/rc.local
mount -t vboxsf -o rw,uid=500,gid=500 linux /home/yourusername/Windows
(linux is the name of the Windows share and Windows will be the name of the PCLOS mount point)
(for the User ID (uid) check PCC -> System-> Manage users on system)
Hope this helps