Thank you for the links. But i found my exact solution like that:
private void listBox1_DragEnter(object sender, DragEventArgs e)
{
e.Effect = DragDropEffects.Copy;
}
private void listBox1_DragDrop(object sender, DragEventArgs e)
{
string gelen = (string)e.Data.GetData(typeof(string));
if (!string.IsNullOrEmpty(gelen))
listBox1.Items.Add(gelen);
}
PS: I am making url check and link check in my codes...