Before you try to use Rocrail to control your layout, you must understand some basic principles and make sure your layout is ready for Digital Control.
The purpose of Rocrail is to control a model railroad layout manually and/or automatically.
Read this first: Track plan Best Practice
The track plan in Rocrail should be a logical extract of the real layout and not a copy of it; Rocrail is not a track-planning program.
Extracting a model railroad layout is not done in a few minutes, but should be planned with sketches on paper to get the big picture before defining it in Rocrail.
Also investigating in internet looking for CTC's could be of help to get an idea on how a real railroad is extracted for controlling purpose.
Take notice that every object in the track plan will use resources from the underlying Operating System.
Avoid adding objects without any functionality for controlling the layout for optimal performance.
You cannot just connect a traditional analog layout to a computer. If you have an analog layout you will first have to convert it to digital operation before you can use Rocrail to control it. This is usually more time and expense than simply building a new layout.
With an analog layout, all devices (locomotives, turnouts, signals, etc.) are powered by raw voltage. Nothing happens until you change the transformer knobs or press the buttons that are connected to your layout. Turning the transformer knob puts power on the track, and so the locomotives start moving. Pressing a button on a switch box sends power to a turnout, and so it switches from one position to another.
This means that when the layout is doing nothing, there is no power flowing to the rails.
With a digital layout, each device has a computer chip in between the rail power and the actual device. Voltage is always at a maximum, because it is used to send information to the chips as well as power any devices. Devices get their power through the chip, and the chip turns the power on and off when it receives a command.
This means that when the layout is doing nothing, the power is still flowing at maximum to the rails. Even if no locomotives are moving or turnouts are being switched, the rails are at full power.
An Analog Layout has simple transformers that supply the power, usually with a controller knob built in to let you vary the voltage. It also uses simple switches to send the power to stationary devices like switches and signals.
A Digital Layout needs a Central Station (CS) to create the complex commands sent to the chips in the layout. It needs a Booster and a Transformer to combine the commands with power for the track.
A Digital Layout requires at least one connection from a Central Station (CS) to your track. The CS uses this connection to send commands to the layout.
Rocrail needs a connection from your computer to your CS, so that Rocrail can control the layout through your CS.
Finally, an optional feedback connection is required from the track to your CS to tell your CS where your trains are, if you want to have automatic operation of your trains.
There are various combinations of these connections, and each layout is slightly different. For example, some layouts connect the feedback portion directly to the computer, because the CS is not capable of understanding the information coming back from the layout.