“Actual or formal argument lists differs in length”

You try to instantiate an object of the Friends class like this:
Friends f = new Friends(friendsName, friendsAge);

The class does not have a constructor that takes parameters. You should either add the constructor, or create the object using the constructor that does exist and then use the set-methods. For example, instead of the above:
Friends f = new Friends();
f.setName(friendsName);
f.setAge(friendsAge);

The default constructor has no arguments. You need to specify a constructor:
public Friends( String firstName, String age) { … }