How to order a collection by a custom property

Suppose you have the following code:

    public class TestItem
    {
        public string Name { get; set; }
        public int Count { get; set; }
    }

    public partial class MainPage : PhoneApplicationPage
    {
        // Constructor
        public MainPage()
        {
            InitializeComponent();
            List<TestItem> li = new List<TestItem>();
            TestItem a = new TestItem { Name = "First name", Count = 1 };
            TestItem b = new TestItem { Name = "Second name", Count = 3 };
            TestItem c = new TestItem { Name = "Third name", Count = 2 };
            //But how do I order the items in the collection by Count property?
            listBox1.DataContext = li;
        }
    }

If I want to order the collection before binding it to the listbox, how do you do that? This is how:

    li.Sort((a, b) => a.SortingParam.CompareTo(b.SortingParam));