It is first better to know for sure if samba has been installed. You can do this by the "rpm" command.
Use the following line:
rpm -qa| grep samba
if you see some samba package shown , then it means that the package has been installed.
If it doesnt show any samba packages, then you can always download the samba package from the Internet at http://samba.org
After you make sure that samba in installed, you can use the "chkconfig" command to manage services, and therefore, samba too..
use the man page of chkconfig to know more.....you cna also use the GUI to get to service management. It shall be availalbe in "System settings ->servers->services"
All the best.