Internet connection

Hello,
I am having the same problem with a new toshiba laptop. I also have a wired dsl connection that goes a through 2 way modem. Two ethernet cords then connect the modem to our two networked desktops. If I disconnect one of those cords from the computer, the computer loses it internet access. I attempted to connect one of those ethernet cords into my laptop's ethernet port, but it did not work. It does not give me internet connection. And any wireless networks that are available I can't access because they ask for a passcode.
Any help would be greatly appreciated.