In the signals editor you can manage the signals of the railway:

In the top list you have to create an entry for each signal on the railway and in the bottom lists you enter the switch commands to be issued for the different signal states. If you do not provide commands for "Slow" or "Shunting", SharpMrc will automatically fall back to use the "Clear" commands instead.

The buttons in the top list show the current state of the signals and can be used to operate the signals.

When the "send on power-on" check box is checked, SharpMrc will send the command to put the signal in its current state every time the railway power is turned on.