With digital command control (DCC) decoders are used to control each locomotive. A model railroader can set the decoders address and control speed, special effects and motor performance etc. Most manufacturers provide programming instructions.
Your DCC decoder may need quite a bit of work on your part if you want it to work properly. DCC decoders need to be programmed which some people find confusing.
The thing is that the systems can be very different. Unless you can build your own decoder you will be forced to use someone else's settings and they may not work for you. Nonetheless, have a look at the DCC decoder schematic and see exactly what your DCC decoder can support.
Luckily there are some DCC decoders that come with the option of DCC decoder programming, such as the NCE and Wangrow systems. In some cases it can be a long and complicated process, but there are some.pdf files out there that will assist you in changing the command station manufacturer's settings. Some people will find this to be a bit too complicated, but there are others that will actually welcome this complication for the chance to run their railroad in the way that they see fit.
The process of controlling the DCC decoder can be made a bit easier with software intended to control the DCC railroad. There is some software that you could pay up to fifty dollars for, and there is some software that will be completely free. One example of this would be the MRC Prodigy interface for DCC controlled trains.
For added control you can always include DCC accessory decoders, which provide more options than your standard DCC decoder. For the most part these are stationary, and while they are expensive, are quite worth having. Some of these have options for auto-return, lock-block, locked route control, system reset, smart default ops, and many other settings. There are a number of reasons why one might prefer to have one of these, away from having a control complex.
For instance if you have your train on display and do not want anyone else to be able to exercise control over it, then you can have the DCC accessory decoders set certain parameters into it. The ability to lock-block will be especially useful in this case.
The only thing you really need to note is that this is not going to be easy by any stretch of the imagination. In some cases you will need to be familiar with computer programming languages, and there are some model train enthusiasts that know more programming languages than some of the seasoned computer technicians. This is can be a big challenge, but it might just be one that you are willing to take on. Are you ready to exercise complete control over your model train set? If so, then prepare to be amazed by the advanced programming and the control of DCC accessory decoders.
The important thing is to be comfortable with the operating system you use. Do not let anyone else in the hobby pressure you into changing from DC to DCC. Some people are comfortable with what they are familiar with and see no need to change to a new system just because someone else raves about it. Both systems have there merits.