Sure, what you have to do is open up a web browser such as IE or firefox and
type in // followed by the ip address of your router, wherewill be prompted
for a username and a password. This number varies depending on the type of
router you have, but some of the more common ones are here:
http://www.microsoft.com/athome/moredone/wirelesssetup.mspx#step3.
Once you have the number, and the default username/password combination, you
should see a page that has all the configurations that your network has.
From here it varies based on router, but there generally are tabs that take
you to different pages, one of which should have something to do with
wireless settings. From here, you go to wireless security, and see if you
have a 'key.' If so, then you have a password. If not, go ahead and create
one.
Post back up if you need further information on these steps, and when you
find out if there is a password or not.
hope this helps,
yasin