C＃：GDI +：使用位图的保存方法过度写入图像

I have an ASP.NET C# page where i am resizing the images in a folder .I am using GDI+ to do this.I want to resize the images and replace with the old images.So when i am trying to save with the existing name ,Save method is throwing an error .But if i give a different name it is getting saved.But i want to have the same file name for the newly created resized image as i need to overwrite the existing file with the new file which is resized. Any idea how to go ahead. My code isI have an ASP.NET C# page where i am resizing t