how should i start?

Sorry, but could you specify your problem a little bit? Does the page not work correctly? In case you see the code editor and just don't know what to type, here is the general pattern for the first task:

public class Solution {
    public static void main(String[] args) {
        //write your code here
        //to display a message you ask the System to print "out" a new line for you.
        //In case of uncertainty, look at the introductory lessons again for the print command
    }
}