As this is the main purpose of this program, there is not really much to tell about it.
First, choose a proper dignorary from the available ones, and copy it to vahunz.ignore. Then create a file list of all your sources you want to vahunz.
Invoke Vahunz without any parameters, and load the resulting
dictionary vahunz.names in your editor. Change the first column of
as many names as possible to plus sign (+), so every
such name will be vahunzed.
Then invoke Vahunz a second time, and specify the command line
option --output with whatever directory you want the vahunzed
files to end up.
If you have other material like a Makefile, copy it to the output directory, too. If all went well, you should be able to rebuild the vahunzed program the same way as the original sources.
If however the vahunzed program does not compile anymore, see the next use-case to find out how to deal with this.