Ok, so here's a very quick introduction to Alpha Channels in bitmaps....
For this example I've just used that Channel 4 image you posted on the last page. I can't stress enough that what follows is a VERY ROUGH example of what to do. With the original images and more time and effort, the results will be 1st class.
So here's what I did.
1) I opened the Channel 4 image in Photoshop:
2) I created a new channel (which is an Alpha Channel by default)
3) In the Alpha Channel, Black is used for areas which are to remain 100% transparent while White is used for areas which are to remain 100% opaque. The shades of grey in between are various levels of transparency.
Using the magic wand and marquee tools ON THE RGB CHANNEL I selected the various separate elements and filled them using the paint bucket tool ON THE ALPHA CHANNEL, thus creating the Alpha Layer you see here. As I said, it's very rough but it should give you an idea of what's going on.
4) I saved the image as a 32bit bmp (then hex-edited out the last two bytes as has been discussed earlier) and imported it into FSHed. The final result can be seen below. (Remember that there is a 'toggle transparency' button in FSHed if you can't see the transparency immediately).
Good luck to you. Hope that helps.
EDIT: I've also attached the .bmp file I created so you can see the various channels in action in Photoshop and in FSHed.