Hi Serge,
Are looking to obtain software that you can install and use, or are you looking for documentation for software you already have?
One type of network management software freely available is MRTG, it will produce graphs of network traffic, a very handy utility:
http://www.mrtg.com/
Another freeware NMS, if I'm not mistaken, is Nagios:
http://www.nagios.org/products/nagiospowered/
We do have some software available for device configuration also (depending on the device). Perhaps the Cisco Netowrk Assistant? You can navigate there from http://www.cisco.com . Choose Support, and under Otion 2, choose "Download Software". Then select "Netowrk Management", "Routing and Switching Management", and "Cisco Network Assistant". Follow the navigation, and you should be able to have a tool to help configure your devices.
Cheers,
Curtis