It's quite straightforward you need a server program on your pc.
If you are using windows 7 or vista the server program is built in. Just open WMP (windows media player) and on the right hand side you see all the libraries that are available at the bottom of this list you'll see your Humax, just click on it and open video then as if by magic you'll see all your progs ready to play. If your lucky, like me, everything will work, if not videos won't play back. You'll need to install new codecs
Alternatively Install a server prog such as XBMC (which has its own codecs), when you open this again you'll see your Humax listed, just open the file you want to watch, voila
To stream to your humax
first
select media > storage > network
you should see your pc or the server you've installed . open it and select the media you wish to watch or listen to.
Sounds easy and in the main it is, remember though the humax is very particular in what it can play video wise.