Tutorial: Object Brushes and Layers - Painting on Trees, Rocks, Vegetation, or any Object
For quickly "Painting" many objects into eitable "Scene Layers".  This can be used for Ground Cover - such as Plants, Trees, Vegetation, and Rocks - as well as for any type of SceneObject (even Lights, Enemies, Buildings, etc.).
Object Brushes have procedural settings for semi-random layout (position, scale, number of objects) and clustering.

Bridge Building (with Physics)
This video tutorial shows the user driving a car around a scene, placing objects, configuring them using Object Editor (for physics settings in this case) - all while the game is still playing (without even having to pause).

 
You can checkout screenshots and short tutorial showing this, as found towards the bottom of this page as well.
 

You can right click anywhere in the Scene Editor and then "Add Asset > ..." to select nearly any asset from Asset Explorer, just navigating through a sub-menu for the Asset Group and one for each "Category Folder" for how its organized in Asset Explorer. 
You can also use right click > Add New > ... context menu to select from common asset types to place an instance of in the scene.  What is shown here can be edited by users by drag-dropping assets in Asset Explorer into the "Base Types" asset group (top-level folder), and can rename existing ones, or group them into subfolders.  This allows you to create your own "shortcuts" for your own custom asset types (eg. a custom "Weapon" or "Vehicle" class, or even specific prefabs / presets you commonly use.

You can also attach other types of Assets to the Scene this way, such as Behaviors, Scripts, Cinematics, etc.

 

You can right click on any Scene Object in Scene Editor, World Explorer or Asset Explorer (as well as a few other types of assets) and select from the "Attach Asset" or "Attach New" context menus, which are used in the same way as "Add Asset" and "Add New" are for adding objects to the scene, except that they are "attached" to an object, so that they are "moved" (as well as scaled and rotated) with the parent object.  
 

You can also attach other types of Assets this way to an Object (or Entity / Actor), such as Behaviors, Scripts, Actions, etc.

4. Advanced Drag-drop for Selecting Attachment Site or Slot

If you hold down the right (instead of left) mouse key when drag-dropping an Asset / Object onto another Object (or the Scene), then you can select "how" you would like to attach an object, or specifically "which" object you would like to attach to (which is useful when you might want to attach to a parent object, instead of the specific Object Part you had drag-dropped onto). 
You can select from the "Attach To" context menu to attach to a certain "slot", such as Moint Points / Actor Attachment slots.

Equipping Weapons and Apparel using Attachment Slots

Additional Documentation

Also checkout the related Assets and Actors documentation:

Assets and Actors - Creating and Placing Avatars and Smart Objects; Configuring Behavior Presets

Manipulating Objects - Moving, Scaling, and Rotating

User Controls for Camera, Mouse, and Scene Editor
Reference sheet for keyboard and mouse controls - both for editing/design using the toolset, and default user controls for demo games.

Placing and Manipulating Objects

Video tutorial showing how to manipulate objects using the mouse, and using the "Object Manipulator" Widget / Gadget / Grips.

Camera and Avatar Controls

Camera User Controls
Controlling Avatars

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Fig. 1

 

 

    In Fig. 1 you have your Architect window. On the left side of the screen, you will find your Asset Explorer container with all the assets that you have in your asset directory. "C:\_realmware\Visual3D_Project\My_Assets\MyGame\Assets". Just a side note. It won't necessarily be on "C:\" drive. It will be on the drive that you installed the program on. 

 

 

 

Fig. 2

 

From this list you will select the asset you wish to drop onto your terrain. The asset can either have the .MESH or the .DAE extension. Once you have selected the asset you want, {Click} and hold down the mouse button and drag it to your scene. as seen in Fig. 3.

 

 

 

 

 

 

Fig. 3

 

And there you have it! It's really that easy. Modifying your asset will be covered in later tutorials.