John
The Trimble Library is also a good place to go to watch Training Videos of key workflows as well as the Community Forum where you made this post. To access the the Trimble Library go to the Support Menu and look for "Retrieve" - to access the Library you will need to have a Trimble ID - if you dont have one - go to www.connect.trimble.com and sign up and then follow the link to Create a New Trimble ID. There are many free videos on the Library and you can also Subscribe to additional videos through the store on the Library. If you need help with the Library, you can work with @Michael Carris at Trimble (michael_carris@trimble.com) and he can get you going with the Library access etc.
For sure you can model Concrete Structures, however as Eric mentioned earlier, TBC models everything as Surface Models so to create a Vertical Wall, the top and bottom of the wall need to be offset by a small amount e.g. 0.01' so that the surface model can be created.
If you have areas in the model that are just a simple vertical offset to the top surface e.g. a Concrete Pad that is 2' Thick or a Concrete Wall that is 6' Tall, then you can simply apply Site Improvements to the areas where the concrete is applied and then use the Create Subgrade command to build the base or top of the surface model - and from there you can compute the Volumes.
If you need help over the next few days as you start this learning process, please feel free to reach out to me (alan.sharp@rockpilesolutions.com) and I would be happy to point you in the right direction. You can also call me on 720 323 0481 if you need to discuss best approach to something.
I would typically start by using the Sideslope Command for both Footings and Structural Walls, that allows you to create all of the linework and Offsets that you need. There are videos on the Blog for PUG 2.0 that you may find useful on this - check out this link - Click Here and take a look at Video for 3A, 3B or 3C or 4 to get a feel for how Sideslope can be used.
For Simple Subgrade Adjustments - take a look at this video at this link
Let me know if you need help
Alan