There are tutorials that come with Bryce 4 in the help menu (move the cursor to the top of the screen if it doesn't show, been a long time since I used 4). This tutorial shows how to create a desert with 2 mountains and a lake cut into the ground. This should get you started. The terrain is usually "sculpted" in the terrain editor by selecting the terrain and clicking the little "e". The dinosaur is simply lowered into the water plane/object so it stands in the water and not on it.