Like @bandit said, you should post your code, your error, and what you are struggling with to fix that error. If you are on 4.) Data Types III: char then it is a simple lesson.
1.
In between the parentheses of System.out.println(); type any single character of your choice. Make sure it’s enclosed in single quotes!
So:
System.out.println('A');
//put any letter in between single quotes and your good!