Configure your LAN connection either for a fixed IP in your local network, or set it to get the IP automatically and make sure you adjusted the values of the DHCP server and the gateway as required in your LAN. In doubt, ask your network administrator.
The USB device you want to use for your internet access: How is this recognised? As modem or as network card? In case you are running Windows, I'd suggest to use the "assistant for Internet connections" for proper setup.