192.168.1.255 is a broadcast address and not much use.
Go downstairs, find a Windows computer that is connected to the wireless router (or disconnect something else and plug your laptop into the router). Open a command window (Start, All Programs, Accessories, Vista/Win 7=> right click on Command Prompt and Run as Administrator, Continue, XP => left click on Command Prompt). Type with an Enter after each line:
The default gateway is the IP address of the router. If you haven't changed the default password to the router then either look it up on the router maker's website or look at http://www.routerpasswords.com/.
That should allow you to get in and read off the wireless encryption password which I assume is what you are looking for. If you have lost the access password for the router then the only thing to do is reset it.