This post originally appeared on the Annexe.
Congratulations, you have successfully installed the MacPorts system. To get the Portfiles and update the system, run:
sudo port selfupdate
Please read port(1) and the MacPorts Wiki at http://trac.macports.org/ for full documentation.
Stray sources might have been left in the legacy /opt/local/var/db/dports directory after this upgrade, which moved most of what it could to /opt/local/var/macports, so you might want to look in the former and cleanup manually.