Nim is a programming languages, so it is FOR PROGRAMMERS!
And Nim may not be the best starting point for someone without any computer experience. Nim is a powerful language, sometimes between C++ and Python, often ahead...
To generate PDF you may try
cd Nim
./koch pdf
That assumes that you have already installed Nim, and you have pdflatex installed.
Or, you may buy Dom's book, Manning offers a PDF version.
For annotations, firefox has plugins for that task for web pages too.
But maybe I fully misunderstand your actual desire.
And Nim may not be the best starting point for someone without any computer experience.
Maybe not the best, but I still think you can start with Nim: shameless self-plug (and it is available as PDF!).
For the documentation, In kubuntu I installed the package "nim-doc.deb" and I found all your documentation in HTML, and thank you "Stefan_Salewski" for your idea " "For annotations, firefox has plugins for that task for web pages too.", it is eaiser than Latex.
For Nim as a starting point: I have a solid basis in "Python" and I used "Tkinter".
Thanks to both of you