SortedList sl = new SortedList();
//creating sorted list.
private void btnAdd_Click(object sender, EventArgs e)
{
if (txtValue.Text != "" && txtKey.Text != "")
      {
        sl.Add(txtKey.Text, txtValue.Text);
//adding key and value to sorted list.
            txtKey.Text = "";
            txtValue.Text = "";
      }
      else
            MessageBox.Show("Text Box Empty");
} 
private void btnDisplay_Click(object sender, EventArgs e)
{ 
ICollection ic = sl.Keys;
//assigning sortedlist key to ICollection variable.
foreach (string str in ic)
MessageBox.Show(str + ": " + sl[str]);
//executing loop for each key avaliable     
 }

Screen Shot