Even a Codeco course wont help, I know, I've done one!
The trouble with it is, it was conceived in the 70's and therefore as well as being ancient is also based on codes. In todays computer world we are spoilt with "tick in the box" programming, codeco doesn't have this and is based on code input. Sadly you also need to know the codes!!!! So no course or manual can really help as the only way in my experience to use it effectively is to just use it and gain comfort and experience with it.
If you get stuck on something then @h is your friend, but even that can sometimes be misleading.
As it is the only system that can control a flight from start to finish (reservations to sita messaging) all in one it is perceived as the god of all dcs systems and those that know it well defend it to the end of the world for some strange reason. Personally I think it is antiquated but that is my opinion.
Send me a PM about what you are planning and I might be able to help out a bit