The following videos should give you a good overview how to use the NodeCalculator.
If you’re unsure whether this tool is interesting for you: Watch an example video first. You might not understand the details, but you’ll see what the NodeCalculator allows you to do.
I recommend to watch the videos in order. They go into more and more detail, so if you feel you know enough to work with the NodeCalculator: Feel free to stop. When you need to understand the tool better, you can come back for the remaining, more in-depth videos.