How to using openfiledialog to take image rather than put one image in program

string pathToImage = @"test1.gif";
pathToImage = AppDomain.CurrentDomain.BaseDirectory + pathToImage;

 //Try extracting the frames
 frames = EnumerateFrames(pathToImage);
 if (frames == null || frames.Count() == 0) {
     MessageBox.Show("Unable to obtain frames from " + pathToImage);
 }

 for (int i = 0; i < frames.Count(); i++)
 {
     ListBox1.Items.Add("Frame-" + i.ToString());
 }

OpenFileDialog dlg = new OpenFileDialog();

                dlg.Title = "Open Image";
                dlg.Filter = "GIF files (*.gif)|*.gif";
                dlg.ShowDialog();

                if (dlg.ShowDialog() == DialogResult.OK)
                {
                    string pathToImage = dlg.FileName;

                }

                
                frames = EnumerateFrames(pathToImage);
                if (frames == null || frames.Count() == 0)
                {
                    MessageBox.Show("Unable to obtain frames from " + pathToImage);
                }

                for (int i = 0; i < frames.Count(); i++)
                {
                    ListBox1.Items.Add("Frame-" + i.ToString());
                }