Good Morning to you,
thank you for your help.
@Unobtainius: no the jar file is not in the example folder.
Solution:
After having some problems I installed the b4j suite, loaded the Forms Builder Project. The problems are easily solved if one followes the installation instruction on the Anywhere b4x download page. That is what I did not correct because I had Java already installed but not the one requested by the install instruction. Killed all my Java and installad it new new following the instruction and now its working.
I compiled the project to a standalone package.
Put the created folders in my b4a development tools folder.
Created a windows file link to the .exe file and added this to the windows start menu.
Now it's easy to open the FormsBuilder Tool by a click to create the jason files.
Thank you for all your comments and please stay away from that ugly covid.