If you want your Raspberry Pi to share its files and folders over the network, you want to install and configure Samba.
Start off by installing the basic Samba requirements:
sudo apt-get install samba samba-common-bin
Edit the samba config file
sudo nano /etc/samba/smb.conf
edit the workgroup= line to match your network. workgroup=WORKGROUP is the default and usually fine. It needs to match what your Windows PCs are set to.
[pi] path=/home/pi browseable=Yes writeable=Yes only guest=no create mask=0777 directory mask=0777 public=no
Add the pi user to samba. Use the same password for the pi user:
sudo smbpasswd -a pi
It takes about 2 minutes for the changes to take effect, but after this you should have no problem exploring files over the network. Note that some may be owned by root and you may have an issue writing to them.
If you have trouble logging in under Windows (password errors), try using “raspberrypi\pi” (raspberrypi-backslash-pi) as your username (without the quotes)