Understanding of CIFS on RHEL 5

Lastnight I read what exactly is CIFS. With some hesitation this morning, I entered on my Linux Command line mount -t cifs //IP address of the Linux system I was on/directory /mnt/ -o user=root and entered my password when prompted. The return was Mount error 13 = Permission Denied. Refer to mount.cfis manpage. As I understand it to be CIFS file systems allow for me to share my Linux folders to Windows Clients in addition to setting up the Samba Share using the Samba GUI Manager. Do I have it backwards and CIFS is for Windows Clients to share there data with Linux Systems. If CIFS is for Linux Files to share there files with windows, how do I setup or format the folder for CIFS?