You need to have the photo stored somewhere on the internet. This might be something already on someones website, or something you upload to some site. Then you need to insert the proper code in your message, to get the photo to display.
I have to relearn the code part every rare time I want to insert some graphic. I suggest you use the "peek" function to look at how others have done it, elsewhere in this (or another) topic.
Adminnemooseus