D’oh. I realise the problem was just that the Output Area was not visible on my WorkBench screen. For some reason when I first loaded it, the Output area was condensed down to just a heading, with no room to see the lines describing the result of each statement, and error codes when applicable.
One first needs to check that the Output Area is not deliberately hidden, by doing menu actions: View > Panels > and looking whether it says Hide Output Area or Show Output Area. If it says the former then the area is currently hidden, so one needs to click the ‘Show Output Area’ option and it will appear.
The Output Area appears at the bottom right of the WorkBench screen. If statement results do not appear, one needs to get the horizontal divider at the top of the Output Area and drag it up so there’s enough space to see the error codes.
Once the error codes are visible, one can sometimes fix the problem from the attached explanation alone. If not, the error code can be looked up to get more info about what’s wrong. Thank to Lucas for pointing that out!