add elements to object array

You can try

Subject[] subjects = new Subject[2];
subjects[0] = new Subject{....};
subjects[1] = new Subject{....};

alternatively you can use List

List<Subject> subjects = new List<Subject>();
subjects.Add(new Subject{....});
subjects.Add(new Subject{....});
// Then you can convert the List to Array like below:
Subject[] arraySubjects = subjects.ToArray<Subject>()