Incompatible Types - Void Cannot Be Converted To String

I have coded three classes ,1 class containing the Main method. I have declared three private data fields in Staff class and two data fields in Address class. The problem is that I am assigning String type data field from the Staff and Address Class through the public set methods to String type array in a public void method in the Main class.

public static void main(String[] args){
// TODO code application logic here
System.out.println("-------------------------------------------------");
System.out.println("Press 1 - 6 To Perform Any One Following Action ");
System.out.println("1. Insert New Contact ");
System.out.println("2. Delete Contact By Name ");
System.out.println("3. Replace Info From Contact ");
System.out.println("4. Search Contact By Name ");
System.out.println("5. Show All Contacts ");
System.out.println("6. Exit Program ");

[Code] ....