Under Windows do double click on the sushi_huh.bat file. Under GNU/Linux open a console and type ./sushi_huh.py or python sushi_huh.py.

After that a console will appear and the default web browser automatically will be opened.
Through the console, you can see where all that Sushi, huh? is doing at every moment.
If your browser does not appear, then open it yourself and write http://localhost:7874 in the address bar.

Select your distribution.

Answer some simple questions, like the version, architecture and repositories of their choice.

Then wait for Sushi, huh? download all necessary files and load the repository.
Finally, the package manager will appear, which you can use to find their packages, get all necessary information and download.

Remember synchronize Sushi, huh? before any downloading, because it will download packages that you already have. If you want Sushi, huh? automatically configure your package manager, you should use Sushi, huh? as root, by typing: sudo ./sushi_huh.py or su <Your root password> python sushi_huh.py

Once maked the synchronization, you can install the packages using apt, yum, urpmi, zypper, etc..
For example apt-get install powermanga
Or using a graphic package manager.