Select image within Panel

A Panel doesn't have a Image property - you will either have to:
1) Put a PictureBox in each panel (and dock it to fill the whole thing) then work with the PictureBox.Image property,
or
2) Draw the image yourself in the Panel.Paint event.

Which you use will depend on what you need - if your images are always those a PictureBox knows, then that may be enough. If you want to do anything with the image in the panel (such as captions, colour changes, lines, boxes, etc), then draw it yourself.

[edit] V2.0
Neither the Paint event nor a PictureBox will select an image for you - you will have to add your own browse code for either. For a quick-and-nasty-but-give-you-the-idea solution, shove in a picture box or two and add a handler for the Click event which routes then both to the same routine.
In this handler, the "sender" parameter tells you which PictureBox was clicked, and you can use the FileDialog class to select a file.

private void pictureBox_Click(object sender, EventArgs e)
    {
    PictureBox pic = sender as PictureBox;
    if (pic != null)
        {
        OpenFileDialog ofd = new OpenFileDialog();
        if (ofd.ShowDialog() == DialogResult.OK)
            {
            pic.Image = Image.FromFile(ofd.FileName);
            }
        }
    }

This code is way from complete - your will want to set filters, etc., etc., but it give you a starting point

[/edit]