Ask for help ubuntu9.10 about Internet access

For help, ubuntu9.10 for Internet access-general Linux technology-Linux technology and application information. For details, refer to the following section. I am using ubuntu 9.10. It is the first time I have installed it on a virtual machine. It is the first time I can directly access the Internet (vro) by running the system in the XP system) later, I updated some software in the update manager and upgraded it to version 10.04 so that I could not access the internet. Then I installed a Virtual Machine (win7 operating system) in my other notebook) after running and installing a CD image file in a virtual machine, you cannot access the Internet on xp for the first time: run the terminal, enter sudo pppoeconf, and press enter ........ I tried the other account and password, but I didn't ask to enter any account and password. At last, the system prompts "sorry, I scanned one interface, but the supplier's Access Concentrator didn't respond, check whether your network and modem cables are connected. Another possible cause of scanning failure is that other pppoe processes are in use ". The younger brother is very confused. He is very interested in linux and is just a beginner.
I also want to learn how to set up networks including wireless networks and routers in ubuntu, as well as those that need to buy the NIC account and password. If you can give me a detailed answer, I am very grateful!