As I wrote in the private message - please just start coding already. Show us that you have played around with examples, try to create something simple, something basic first and then move on to more complicated stuff.
You keep asking about "linking the code to ui" - just open any example in :widgets: section in Qt installation, try to change the code, compile and test, observe the behaviour and draw conclusions.
You can't solve this problem without getting your hands dirty.
Leave the "indexing" issue aside for now, try to create a simple app to display the file stats in a widget. I think this is the best way to know new library or framework, by creating more and more complicated stuff from basic "building blocks".