Before you do simulation, define a stock.

You can start the simulation from the menu

or from the tool bar

You will then see the simulation window.

The simulation window can be resized.
Use the mouse wheel to zoom in and out.
Click and drag to rotate the view.
Press the Play button to start the simulation.
The Pause button will stop the simulation.
The Rewind button will restart the simulation.
The Initial View button will reset the view point.
Increase or decrease the speed of simulation with the slider.