I am trying to develop a Windows Mobile 6 (in WF/C#) application. There is only one form and on the form there is only a PictureBox object. On it I draw all desired controls
You can get an Bitmap object from your controller and then assign it to image property of PictureBox. You should also dispose the current image of PictureBox to release the resource.
var bmp = controller.GetBitmap();
pictureBox1.Image.Dispose(); // this releases bitmap resources, required
pictureBox1.Image = bmp;