Error: Module not specified (IntelliJ IDEA)

I was trying to execute a simple program in IntelliJ IDEA as a static web project. I'm newbie and I'm learning web development with Node.js. I took help from the official website of IntelliJ IDEA, but the error was same. Though, I configured the settings and Project structure also.

Error:

"C:\Program Files\Java\jdk1.8.0_91\bin\java" -Didea.launcher.port=7535 "-Didea.launcher.bin.path=C:\Program Files\JetBrains\IntelliJ IDEA 2016.1.2\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\JetBrains\IntelliJ IDEA 2016.1.2\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMain ""
Exception in thread "main" java.lang.ClassNotFoundException: 
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:122)

Process finished with exit code 1

Snapshot of IDE

Please help me to sort out this problem. I'm digging out this problem since few days.

This is because the className value which you are passing as argument for
forName(String className) method is not found or doesn't exists, or you a re passing the wrong value as the class name. Here is also a link which could help you.

1. https://docs.oracle.com/javase/7/docs/api/java/lang/ClassNotFoundException.html
2. https://docs.oracle.com/javase/7/docs/api/java/lang/Class.html#forName(java.lang.String)

Update

Module not specified

According to the snapshot you have provided this problem is because you have not determined the app module of your project, so I suggest you to choose the app module from configuration. For example: