I want to be able to enable my authors to have an ad at the bottom of each post in single.php. I have played around with a few plugins like author signature and author image but they don't allow me to do what I want. I have also tried messing around with conditional tags and can't seem to get it. I am just a beginner with PHP.
Does anyone know how I can do this. If you have a conditional tag solution, that would be best but if not, I am open to any ideas. Thanks.