Questions about the Heroes 4 map editor.

I've already created the Dungeon, but I'm still having trouble with the portals – they don't lead anywhere. What should I do?

If you mean the lists in the Dungeon/ascents to the surface, then if you only have one entrance to the Dungeon on your map, you can place the list/ascent anywhere. If you have multiple entrances, you should only place the ascent directly below the descent – i.e., on the upper level, place the descent in one location, and on the lower level, place the ascent in the same location as on the upper level.