Static fields and methods are connected to the class itself and not its instances. If you have a class A, a 'normal' method b, and a static method c, and you make an instance an of your class A, the calls to A.c() and a.b() are valid. Method c() has no idea which instance is connected, so it cannot use non-static fields.
The solution for you is that you either make your fields static or your methods non-static. You main could look like this then:
class Program {
public static void main(String[] args){
Program programm = new Program();
programm.start();
}
public void start(){
// can now access non-static fields
}
}