If the output of "echo $PATH" doesn't look like the following then you need to change your ~/.profile
Code:
Mac-Pro:~ tom$ echo $PATH
/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin
To edit the file in the terminal, type the following:
You should see something like this:
Enter in the PATH and MANPATH lines I posted earlier. To save and exit, hit ctrl+x and then y to save.
Then after doing that, either close the terminal and go back in or type "source ~/.profile" to update your paths in your existing session.
Once you do that you should have access to the port command. You'll need root access to use the command though so run it with sudo. For example "sudo port install squid."