Absolutely not a dumb question. If you have more questions after my explanation, please feel free to ask.
Corsi means ALL shot attempts (including blocked and missed shots) by either team in a game.
Let's take examples from the 11/11/15 ONT VS SJ game to further illustrate.
In this game, Ontario outattempted San Jose 55-41. Meaning for Ontario, their CF (Corsi For) was 55 and their CA (Corsi Against) was 41.
So that's the team level. Now let's talk about on an individual level.
For the aforementioned game, Michael Mersch posted a 26-7, or in other words, a 26 CF (Corsi For) and 7 CA (Corsi Against). This means that he was on the ice for 26 attempted shots by Ontario and just 7 attempted shots against Ontario. So for 78.8% of the total shot attempts that he was on the ice for, it was Ontario attempting a shot, or a 78.8% CF% (Corsi For %).
These are excellent numbers for Ontario and Mersch. For further explanation of why Corsi matters, the Jewels article cited above by PJ should help. And again, feel free to ask more questions.