DownloadData with AsyncTask -sample-

private void button1_Click(object sender, EventArgs e)
{
DownloadImage();
label1.Text = "Resim indiriliyor.";
}

private async void DownloadImage()
{
WebClient client = new WebClient();
byte[] imageData = await client.DownloadDataTaskAsync("https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgChuJbZJK7yt73JXEbETEWdrrUpKxSddrSLgAf3DGNdT4OAgytVPI7SHrEyaljO3AuqhHPn8Ziqv4haZ8hAqgpY4DQOY1qjWJrjQ7dB0OKcmRKCy7E7ePW1oPiDWRcFPGFYTqGOq5oNF1A/s640/1.PNG");
this.pictureBox1.Image = Image.FromStream(new MemoryStream(imageData));
label1.Text = "Resim indirildi.";
}