Start small. Download the free Class 742 shuttle on the Jihlava branch line. Learn to stop the train exactly at the "S" board. Once you feel the rhythm of the Czech signals changers, you will never want to drive another virtual train again.
If you are coming from German or US simulators, forget everything you know. railworks cz sk
The official DLC from Dovetail Games is solid, but the freeware community (often hosted on sites like TrainSimCZ or VagonWEB ) rivals payware quality. Many locomotives feature fully functional cab displays in Czech language, realistic door controls, and even working Rychlosti Jízdy (speed charts). Start small