C Sharp :: Error Concerning Sorted List Not Being Accessible Due To Its Protection Level

For school we have to create a blackjack game using windows form. I had to store the images of each card into a sorted list so i created a class called cardList and created a constructor which contained the the sorted list called cards. So it looks kinda like this:

public class cardList : Form1
{
SortedList cards = new SortedList();  
public cardList()

[Code]....

There's probably a few other errors, I'm still trying to figure this whole c# thing out. why the error tells me (on the line that contains c.cards.GetByIndex(cardNumber);) that cards is inaccessible due the its protection level.