Welcome to the Ranch
Please don't download lots of IDEs until you have tested a few things at the command line/terminal.
Open a terminal and run the following two commands:-
You should get version numbers for both, and the version number for
javac shouldn't be larger than that for
java.
Navigate to the directory where your
XXX.java files should be, and execute
dir (Windows®) or
ls (*nix) and confirm that all the files are present.