Changes to an android app including api server, mysql and php pages

I have an android app which needs the following changes making. The admin user needs to be able to upload images to the special offer and gallery part of the app. These will be view able by guest users.

These images will be sorted on an api server, so they can be accessed by iOS, so knowledge of android studio/java script/my sql and php is needed for this project.

I would also need some basis training on how to change the rename the database in the code for the app and the location of the api server php pages.