Thank-you, everyone.  It's working now :)

Thanks  for the reminder.  I completely forgot about Leo and the 2D image editor (d'oh!) 
However, I've managed to lose the information I had on how to build a lunar surface in the terrain editor too, so a reminder there could be handy too :)

 Thanks for the tutorial, electroglyph.  I'll see what I can do and put up the results in the gallery :)

Thanks very much for the replies, and especially thanks for the tutorial.  I'll get to work on it asap.  :)

Okay - next question: the Poser textures tend to be pretty flat and unrealistic with the light sets that I've got; people tend to look as if they've been painted, rather than having 'natural' skin.  I know that Poser 4 limits the range of what I can do here, but does anyone know if there's a package anywhere I can use to give skin that realistic 'look'?  I'm talking here about, say, the reflection of perspiration, or the glow that skin reflects if a blue light is shined upon it - that sort of thing.  I'm pretty much an amateur here, so if there's a way to get these effects without downloading a package, please tell me.

Thanks.

Thanks, everyone. That did the trick. I'll postwork it and put it in the gallery later :D

Okay, I've rendered the model as a black-and-white image and saved it as a PSD file. Could you be more specific about what do do next, please? I've opened the Universe background and the B&W PSD, but I'm not sure I'm reading your instructions correctly.

You could try using a volumetric slab - I don't tend to use them much myself, because they can push the render time right through the roof, but if you Alt-click (or it might be Ctrl-click - it's one of them!) the water terrain button at the top left of the Bryce toolbar it will create a "block" of water rather than a 2D plane. You can apply a suitable water texture to this "block", which can then be stretched up out of the field of view. Then you can play around with the light settings for that lagoon or abyssal depths look. Word of warning about volumetric renders, though: I'm not kidding about the render times - they can be enormous, so if you're looking for a quick fix to your problem this may not be it. That's why I tend to avoid them (I have no patience!) IIRC, there's one volumetric-slab render in my gallery titled "Pollution". It's nothing special but it should give you a basic idea of the potential of the voluemtric slab. Hope this helps.

Thanks, everybody. :)

Thanks for the suggestions, everyone. I've installed the 5.01 patch now and that's sorted out the problem. As for the castle, at the moment I've got the foundations/floorplan built, as well as parts of the turrets and the roof. Just need the bit in the middle now. Any good building stone textures would be welcome, though :o)

Thanks. I'll get right on it :)

Well, McDetti's 'Dezember' (in the Challenge Gallery) definitely gets my vote. It's gorgeous :)

iJack999's Electric Studabaker gets my vote, because it's a nice, simple blend of retro and modern. It actually looks like something you'd see on the roads in the near future, and here's the clincher - it looks affordable as well!