Answering to your comment:
A counter is just an int variable that you can increase.
Here are a few links, you should take time to get a basic understanding of OOP programming:
Classes (C# Programming Guide)
C# Lists examples
Create a Multiple Choice Quiz with arrays in C#
These are only some general guidances to show you how you can structure your program in an OOP way; they are not a direct solution that you can copy/paste.
You should first study a little bit of classes and lists, then take a pen and paper and write down the process using your newly acquired knowledge. It is quite hard to give you meaningful guidance since we do not know how much of c# development you already know; the only thing that can be said is that the way you first considered to architect your program will come and bite you very quickly.
Finally, here is some kind of general algorithm to help you started:
int counter = 0;
List<Question> questions = new List<Question>();
List<Question> wrongAnswered = new List<Question>();
for each (Question question in questions) {
}
for each (Question question in wrongAnswered) {
}
Hope this helps. Kindly.