Personally, I do all of my JBeaming in Blender just like in the tutorial on the wiki. It doesn't give you any control over node numbering order (it almost seems random) but it makes a big job very very easy. Once I have the structure that I desire, I then use Sublime Text 3 or Notepad++ (depends what computer I am on) to enter everything else.
You "write" your vehicle's parameters into existence. That might not make much sense, but that is exactly what you are doing.
When doing scrarch jbeams I also start in blender, but for further working on it or for editing content I use the Node Beam Editor: https://www.beamng.com/threads/nodebeam-editor-v-0-37.6103/ (You can also find it in the game files). It makes jbeaming a lot more intuitive and faster IMO (in fact I couldn't be bothered with jbeaming if it wasn't a thing). You have to be careful though since it sometimes does weired things and there is no undo option, saving files regularly is important.
I downloaded the nodebeam editor but I can not figer out how to use it (like make the program appear because I only have a zip)
You need to unzip the program first. Also, if you have problems with a simple ZIP file, I'm afraid you will find Jbeam impossible, as it's pretty complex and technical.
OK now I have something to jbeam, but obviously I will finish off mesh work first. I managed to get it working!