N.B. only when the installation program detects the presence of network interface on your PC this configuration step appears.
Configuration of the network serves two purposes:
Even if you are installing using CD set, you may need network operation after installation.
At CSE, we have permanent internet access, it's better to set it up.
At Home, you probably have only broadband or dialup network access, it's better to postpone the network setup until the system is installed.
. . . press the "Next" button at the bottom to proceed.