On the main screen one can open the configuration of the controls with the icon :

In the example abouve there is already a configured control with the name "My Control".

At the bottom there is a button named "New" to add a new control to the configuration.

Usually there is only one control per modelrailway layout. For bigger layouts it can make sense to use more then one control, so there is a control for the locomotives, one for the accessories and one for feedbacks.

Acutally RailControl supports the following controls:

Manufacturer Control
CAN-Digital-Bahn CC-Schnitte 2.1
Digikejis DR5000 (configure as Roco Z21)
ESU ECoS/Central Station Reloaded
Fleischmann Twin-Center
LDT HSI-88 RS232
Märklin Central Station 2/3 with TCP (new)
Märklin Central Station 2/3 with UDP (old)
Märklin Interface 6050/6051
OpenDCC OpenDCC Z1
Roco Z21/z21
Tams MasterControl
Uhlenbrock Intellibox