Wi Fi or Hardwire

I recently moved into a basement apartment that has a router in it.I can't use it because,after my laptop aquires the signal,it says I have to have the key (which I don't have). There is a modem inside the electrical panel. I hooked a wire from its ethernet port to my laptop and I still can't use it. Right now I am getting a s0-so signal fro somewhere in the neighborhood. The lady upstairs has internet and I know it is hooked into this one ,downstairs. How can I use one of these good signals ?