Clients that use the pre-installed operating systems already have their servers network pre-configured with a static IP addresses; there is no more need for any manual setup. If you, however, decide to upload your own custom ISO and install the operating system yourself, you will need to manually configure your network.
You can find the relevant information (IP address, subnet and gateway) regarding the IP addresses assigned to your virtual servers in on the servers management view by hovering the IP address with your cursor. Positioning your cursor over the IP address should show a tooltip with subnet and gateway.
Should the operating system of your choice ask for a netmask or network mask: this information is not directly displayed, but you can figure this information out through the size of the subnet. Most parts of our network are split into /26 subnets and the netmask for /26 subnets is 255.255.255.192. Should you still struggle to find the correct network settings, feel free to open a support ticket!