To add a comment you just need to click your name in the list of people attending and enter what you want to say. Once you've clicked your name we remember who you are so the next time you view that calendar you'll already be selected.
This also means we know when someone re-visits a calendar, which we hope to build new personalised features with, like 'Show me everything that's changed since I last visited' or 'Link my availability across calendars'.
As ever, if you have any ideas for new features or things you'd like to see Meetifyr do then please let us know.