Replace Previous Uploaded Image

Using the GD Library, how do I display an external image, on the canvas, whilst displaying the following centered text.

Text to Display: "Image 1"

See this and the examples they show:
http://us3.php.net/imagettftext

The nice thing about using TTF is that you can provide your
own true-type-font file, so the text can be any font you wish.

They have examples that explain about centering text, and
some discussion on multiple lines of text (which is more difficult).

You didn't provide an image for us to play with, or any indication
of the font you would like to use, or font size, font color, etc....
so we can't provide much more than a link to the GD website.