The TUI (text interface) is the console part and is usually found below the graphics window in the default view.
Scheme and rpvar commands are not something I'd recommend messing with unless you REALLY know what's going to happen. You will need the brackets, apostophies etc and they must be in the correct places. Otherwise they'll either fail, or do something interesting to your model, often both.
You are navigating away from the AIS Discovery experience