What pterm does is to log you on to a computer where you have an
account. The nickname is just a name you choose identify that
computer and the choice is up to you, while the host is the internet
name (such as
google.com) of the site. You will need to enter your
userid on that site, and will be asked for your password when you are
connected.
Maybe you wanted to use pterm to log on to your computer. In that
case go to 'sharing' in its system preferences. You should see
somewhere indication of the host name to use (e.g. mycomputer.local)
if you're currently on its network, or its name for outsiders (e.g.
mycomputer.ntlworld.com) otherwise. You'll need to enter your userid
for your computer, and the password on connection if your account has
one. Also, you'll need to enable remote logins in the sharing
preferences (somewhat risky!). The outcome when you're logged in is
just the same as if you were to run Terminal or X11 on your own
computer.
Now I'm just waiting for someone to answer my own question!
Brian