Can anyone coach me through how to use java on my Mac?

I am a new programming student and my professor is lacking in teaching skills. Can anyone help out on how to get started on java with compiling a HelloWorld program? I know I go to terminal on Mac and I tried using TextEdit to type the program but I am at a loss on what to do next. I need help! Also I’ve watch tutorials on Youtube but mine doesn’t seem to go along with what they are doing.