This code snippet shows how you can set your PictureBox's image to be the image from the clipboard:
[C#]
pictureBox1.Image =
(Bitmap) Clipboard.GetDataObject().GetData( DataFormats.Bitmap );
[Visual Basic]
pictureBox1.Image = _
CType(Clipboard.GetDataObject().GetData(DataFormats.Bitmap), Bitmap)
Contributed from George Shepherd's Windows Forms FAQ