Photo image

I have a photo of our pre-production poster up that needs to be replaced. I uploaded the new one with an actress's name that is spelled correctly.  There seems to be no way for me to replace it manually on my own. I created the dang site.  I submitted a request to change the image to IMDb, and they declined, saying it was not formatted correctly.  I just want to change the damn photo image. The actress is on my butt about it. This should not be that hard to do.  What is the trick here?