static void Main()
{
    Form frm = new Form();
    frm.FormBorderStyle = FormBorderStyle.None;
    frm.ShowInTaskbar = false;
    PictureBox pbx = new PictureBox();
    pbx.Image = 图片;
    pbx.Dock = DockStyle.Fill;
    frm.Controls.Add(pbx);
    frm.Show();
    Thread.Sleep(3000);
    frm.Close();
    // 启动软件主界面
}