[hardwired]

All this

Code:

Account[] accs = new Account[1];

does is to instantiate an array of type Account and length one.
The only (and every) element of the array is null. To initialize the first/only element
you would call a constructor of the Account class. It looks like you did this with

Code:

accs[0] = new Account( "Pauline Smith", 300, 250 ) ;

and got the compile error which is saying that the Account class does not have a
constructor with the signature

Code:

Account(String s, int n1, int n2)

You can add a constructor into the Account class with this signature if you like.