A data sheet for the part will be much more useful than a photo. Or, at least tell us the part number so that we can find a data sheet, if we are so inclined.
I have seen a few diagrams but just need to understand physically how to do it.
When you mention something that you found on the net, why not link to it so that we know what you know.
That part may be a phototransistor, not photodiode.