Each tutorial will explain how a particular feature works (such as the OK light [or ACT light if you have the new RPi], the frame buffer or input).
These features are implemented in functions, and the main function calls them (AKA 'branches' to them, in ARM ASM terminology) in a way that is specific to what you want to achieve.
So, if you want to implement a flashing light, while drawing to screen and getting input, you as the programmer must decide how you put it together. Essentially you will use the main function to call these other functions with the input that you decide upon, depending on what outcome you want to achieve.
I have ordered Bruce Smith's – A Hands On Guide to Assembly Language on the Raspberry Pi so I no doubt could wait till then to find out
Have you started the tutorials yet, or are you waiting for the book first? The tutorials will explain how to implement the functions in main. In my opinion, you don't need the book to start the tutorials. It may be useful to build on what you learn, but not necessary to start.
I hope that helps in some way. It's a bit of a 'how long is a piece of string' answer.