You need to join a channel after you connect.
Try this to see...
Type:
/server irc.undernet.org
After connected:
/join #help
If it says you need to be registered, then you have to register your nick on the network to use the channel. Networks don't all do this the same way, so you should go to the #help channel on whatever network you're on and ask how. Sometimes those instructions are in the #help channel's topic. Just as a note, most servers that ask for you to be registered probably use Nickserv. If that's the case, typing
/nickserv help will give you the list of commands (including the REGISTER and IDENTIFY commands). Once registered, you have to activate the account (check your e-mail for how). Then, everytime you connect, you need to identify (i.e. log in) to your registered account.
