how to download audio file from uri and save in local folder in windows phone 8?

////// For Download and save
private void addButton_Click(object sender, RoutedEventArgs e)
{

WebClient webClient = new WebClient();
webClient.OpenReadAsync(new Uri("https://dl.dropboxusercontent.com/u/65265347/dog38catsi_a2yn44rm.mp3", UriKind.RelativeOrAbsolute));
webClient.OpenReadCompleted+=webClient_OpenReadCompleted;

}



void webClient_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
string fileName = "createmytone.mp3";
Debug.WriteLine(e.Result);
using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
{
if (myIsolatedStorage.FileExists(fileName))
{
myIsolatedStorage.DeleteFile(fileName);
}

using (IsolatedStorageFileStream fileStream = new IsolatedStorageFileStream(fileName, FileMode.Create, myIsolatedStorage))
{
using (BinaryWriter writer = new BinaryWriter(fileStream))
{
Stream resourceStream = e.Result as Stream;
//streamResourceInfo.Stream;
long length = resourceStream.Length;
byte[] buffer = new byte[32];
int readCount = 0;
using (BinaryReader reader = new BinaryReader(resourceStream))
{
// read file in chunks in order to reduce memory consumption and increase performance
while (readCount < length)
{
int actual = reader.Read(buffer, 0, buffer.Length);
readCount += actual;
writer.Write(buffer, 0, actual);
}
}
}
}
}
}
//// Set as Ringtone
SaveRingtoneTask saveRingtoneTask = null;
private void setRingtoneButton_Click(object sender, RoutedEventArgs e)
{
try
{
string isoStorePath = string.Concat("isostore:/", "createmytone.mp3");
saveRingtoneTask.Source = new Uri(isoStorePath);
saveRingtoneTask.DisplayName = "My Ringtone...";
saveRingtoneTask.Show();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}