In your custom event drag de red square and type: set timer by event, make it loop.
add a branch, in that branch u will have to check if your key/button is pressed, if it’s true, execute de fire 
In your custom event drag de red square and type: set timer by event, make it loop.
add a branch, in that branch u will have to check if your key/button is pressed, if it’s true, execute de fire