Thank you very much for your reply, it worked, my enviromental varibles were wrong, but know it works.
But I have still an issue, after setting everything up the "MDKexample" (the template project) is missing.
I tried to delete everthing and to reset everthing but that file is still missing.
-i used the command "gradlew genEclipseRuns"
-after that i also used the command "gradlew eclipse"
-both were successfull
-than I started eclipse, and selected the main folder "MyMod" --> no files
-than i tried to search for the file manualy --> no files
i would be very thankfull for another advice
ps.I probably should make a new topic for that question