Manual Firing Mode - How Do I Tell The Fireman To Add More Coal?

I’ve just been opening and closing the firebox but it doesn’t seem to do a lot, getting no where near enough pressure.

What exactly am I meant to do/click to add more coal?

 

You ask him very very nicely, after all he has a spade and you don't

 

Open the firebox door, he's a smart fella that fireman and he takes the hint very quickly.

 

You have to looked him dead in the eyes, and speak the word’s “it’s the coal or you know. You.”

you’ll soon see their a dedicated and motivated employee.

 

*Stares at the firemen*
ADD MORE BLOODY COAL YOU DOUGHNUT