To set a static IP address, start the Alta VM, log into its desktop, and go to "Applications Menu" > "Settings" > "Network Connections". Choose the appropriate NIC (which physical connections come up is determined through the VirtualBox menu described in the previous step - if there is any question about which NIC is which go to "Ethernet" > "Device MAC Address" and match these values up to the ones in the VirtualBox menu), and go to "IPv4 Settings". Change from "Automatic (DHCP)" to "Manual" if needed, and then add the desired IP address, netmask, gateway, and DNS servers as appropriate. For this work, the IP address and subnet have to be appropriate for the network that is being reached through the physical adapter that is reached through the VirtualBox settings for this virtual NIC.
Linux command line tools such as the "ip" command may also be used inside the Alta VM. Check the appropriate man pages or reference guides.