实现效果:

知识运用:
File类的Copy方法
public static void Copy (string sourceFileName, string destFileName)
实现代码:
private void button3_Click(object sender, EventArgs e)
{
foreach (object o in listBox1.SelectedItems)
File.Copy(textBox1.Text + "\" + o.ToString(), textBox2.Text + "\" + o.ToString());
}