promo don't say a lot ;-) but guess you have a main cave.obj and then lots of other .obj's (pointy bits (yas I know but cant spill ) rocks ladders woteva

import the cave (untick all on import) check scale (poser uses a tiny scale ) adjust (and save out if you going to use it a lot, mats may or not load so expect to adjust them

now import the next prop you want scale (same as main cave for now ) place it where you want it, adjust scale more to get it just how you like it

now parent it to the main cave on to next prop be a bit boring for next while so once you have a really nice setup save it as a scene file in case you want to reuse it

cant see on there what proggy it was made in but some proggys make huge models (compared to poser) so on import if you don't see it scale it down and try ctrl+d, or check to see if your inside it (try pose cam)

hope that helps a little