各位给个正确的  感激 感激！！！

namespace SeasonImage
{
    public partial class ListBoxSeason : Form
    {
        public ListBoxSeason()
        {
            InitializeComponent();
        }
        enum Season {
        spring,summer,autumn,winter
        }
      private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            Season season;
            int index = ListBoxSeason.Selectindex;
            season = (Season)index;
            string filename = @"D:\Image\Season" + season.ToString + ".jpg";
            pictureBoxSeason.Image = Image.Form(filename);

        }

运行后有以下错误，我不知道怎么改啊！！！
1.已在此范围定义了名为“index”的局部变量。
2.“SeasonImage.ListBoxSeason”并不包含“Selectindex”的定义    
3.运算符“+”无法应用于“string”和“方法组”类型的操作数
4.“System.Drawing.Image”并不包含“Formfile”的定义