Try this exercise on your own machine.
Create a new file called Greeting.java.
Write a class named Greeting with a main method that prints your name.
Open a terminal and compile the file with javac Greeting.java.
Run it with java Greeting.
Verify your name appears in the terminal output.
Once that works, try breaking it on purpose. Remove a semicolon and compile again. Rename the class to greeting (lowercase) while keeping the file name Greeting.java and compile. See what errors you get. Reading error messages now saves you hours of confusion later.