Follow these steps:

1. In the Simulation Frame, select the Source MAC Address and the Destinaton MAC Address.
2. To begin the simulation, click the 'Start Simulation' button.
3. To simulate again, first click the 'Reset' button.
4. Try out the other devices just by clicking on the dropdown visible at the top stating Choose a Network Device.
5. If you want to exit the simulation just close the tab.