If your wifi adapter (probably wlan0 or ath0) does not say "UP BROADCAST MULTICAST"
then it is not on.
In that case try
then check your connections again with the "ifconfig" command. (iwconfig does not give you as much information)
Assuming that is now working:
go to dragon icon --> Internet --> Wicd Network Manager
There you can see what networks you wifi can connect to, as well as enter the password for the desired network.