DarwinPorts can be installed from source too instead of from the dmg images. Download package DarwinPorts-x.x.tar.gz, and put it in your home directory. To see it is there, in the terminal type
ls
and press Enter. Unpack the tarball, by typing
tar zxf DarwinPorts-x.x.tar.gz
(where x.x is the version number, e.g. DarwinPorts-1.1.tar.gz). Change to the package directory, by typing
cd DarwinPorts-x.x
(x.x is version number). To configure the package, type
./configure
To compile the package, type
make
Finally, to install the package, type
sudo make install
and provide the password it asks for.