When you download a fresh copy of IgnitedCMS, your project will have the following folders and files in it.
At first glance the sheer number of files and folder can seem daunting, but don't worry, there are only two real places you will be spending most of your time inside. The template directory which is under:
application > views > custom
and possibly the custom controller directory which is under:
application > controllers > custom
This is where you might write your own custom controllers to communicate with a new table in the database.
The place where all your uploads are stored is contained within the folder:
assets > uploads
You shouln't need to touch any other files, as the ignitedCMS engine does everything else