Take a look into the TeapotWars.cpp at the bottom is a function called TeapotWarsGame::VBuildInitialScene() that's the function which creates the terrain.
So static geometry can be added there (but only the data representation, the graphics part is in the view!)

In TeapotWarsView.cpp you can change the look of the teapot for example by changing the function CreateTeapot.

In both files are function for other geometry, too. You've got always a data representation of it in the TeapotWars.cpp and the graphics model in the TeapotWarsView.cpp

A health pack is a little bit more work, because it offers the game more interactivity. Basically you need a model for it in the view and in the game a data representation (a position vector for example). And you need a trigger zone which makes it possible to pick the health pack up.
Triggers are already in the physx sdk, so this would not be that much work.