I like to call the rest "trigger code". This is what is going to trigger from your code. Now now, before we get into it, remember this one principle, where you see any colon, there is 4 spaces, or 1 tab:
Incorrect:
on break:
give player 1 of diamond
Correct:
on break:
give player 1 of diamond
Remember also, that you can not switch between tabs and spaces. For example, you put 4 spaces once, then on the next line, you put a tab. This will give you an "expected xxx number of spaces" or "expected xx tabs" error.
Alright, now, let us get to it. So, as you can probably tell, trigger code is what is going to be triggered. This has to be in a format too, let me give you an example:
Incorrect:
on break:
give player one of "diamond"
Correct:
on break:
give player 1 of diamond
Find a list of this on this website, there is really no specific one, as there can be a wide variety of classifications for different types:
https://en.njol.ch/projects/skript