change in network access point, have to add a password, can't figure out how

Hi, my girlfriend rents a room in a house and the woman has made some
sort of change to her wireless access hub so that it now requires a
password to log onto. She was given the router number, told to find
it, press connect and enter in a password. So she used the d-link
configuration utility and it lists the router. But when she clicks on
connect she gets the message "access point network is already
configured change name or network type before adding entry to
preferred list." I tried to figure it out but I just can't figure out
how to put in a password. I tried the d-link software and on a guess
had her set authentication to WPA, whatever that is, and that allowed
her to put in a user name (which she doesn't have) but not a
password. I also tried the home network wizard but couldn't find
anything there to add a password. It seems like there should be a
simple way to do this, but it's beyond me.

She's got a d-link dwl-g122 air plus g wireless 802.11g, and I don't
know if this is more a d-link thing or an ME thing but I can't seem to
find anything pertinent on either end.

Anyone know what on earth she needs to do?