Update Android app Content Dynamically

Basically I'm making an android app and I would like to be able to add content dynamically without having to update the app. For example I would like to add a image to a server and then it be updated in my app. Can anyone give me some guidance on where I can get started? Should I be using php, mySQL?, or something else? In addition, if there is something that I can get in the asset store for this then that would be even better. Haven't been able to find anything so any advice would be great! Thanks