insert a image in the ImageList at the perticular index

Question

I want to insert a image in the ImageList at the specified index or you can say that  replace the existing image at the perticular index but the Add method can'nt able to resolve this issue ,
imageList.Images.Add("w",Image.FromFile("C:\\Folder.jpg"));
Or,
imageList.Images[listView1.SelectedItems[0].Index]. ????
what can i do????