Hrm. Also.... it looks like the Working Box is not visible in your screen shot, Ariana. I assume that since "icy moon" is a space scene who ever constructed that scene turned it off. The Working Box is a set of three grids, sort of like an empty "Voyager" Holodeck, that can help you to orient yourself in 3d space, give you a ground plane reference, and in general help you to gather up the elements of a scene. (I generally hide the two sides and keep just the ground, myself). As Sparrowhawk says; you don't, basically, model a mountain or anything else in the Assembly Room. When you drop an object into the Assembly Room (from the menu at the top), you will automatically transferred to the Modeling Room for that class of object. If you insert a "mountain" (aka a terrain), you will be sent into the terrain modeler, which has a specific workspace for creating terrains; a fly-around preview, paint tools, fractal tools, etc. If you insert a "tree," Carrara will open up the tree modeler; a set of pages with previews that lets you set the parameters of a procedural....ah, palm. (And Peter picked a peck of pickled peppers...) And so on and so forth. Each kind of model you insert pops up some sort of interface that is specific to that model, with the tools to work on it. Another method of populating your scene: The "handle" on the bottom center of your display, if tugged, opens up the Browser Window. Within your browser are, among other things, many pre-built models. Don't know if these late thought will help the OP, but they might help someone....