i cant find the problem

You need to be aware of where your capitalisation is. Such as when declaring a string variable, it needs a capital "S" - String.

This would mean the following should work once you've corrected the capitalisation of String, and using console instead of Console because you've declared a variable for the Console.

Sometimes I find changing the variable name useful, such as Console consReplace then I'd put in consReplace.printf

// I have setup a java.io.Console object for you named console
class unidentified
{
  public static void main( String[] args);
  {
  Console console = System.console();
  String firstName = ("jainil");
  console.printf("%s is a rockstar",firstName);
  }
}

Check out this code and see Your errors. They are so basic that u might think about writing some BASIC code on your own. Starting by printing "Hello World" using System.out.print, Console (and anything used in the courses in Treehouse). Check if they compile.

Write one line of code -> compile -> run.

When there are error messeges learn how they look and what they mean. It is in the course as well. Just practice practice.

// I have setup a java.io.Console object for you named console
import java.io.Console;

public class Unidentified
{
  public static void main(String[] args)
  {
  Console console = System.console();
  String firstName = ("jainil");
  console.printf("%s is a rockstar",firstName);
  }
}

you don't need to write all that , the task is in three part so just write what your ask simple. for example the first part of the task is asking you "Define a string variable named firstName that stores your name. Set the value to your name." so the answer is String firstName="jainil jaha"; then compile it.

NB: java is case sensitive.