How to add a gig in the calendar (just in case) (one of the ways) :
You go in the Concerts and gig board, click on "New event" (instead of "New thread") then you fill up the name (if you could put it like "Mika @ venue - city" it would be great as the calendar would be uniform...), then the date of the event, and then a little description with the website where you can buy tickets if you have an address...
The event has to be approved by an admin to appear in the calendar, and this will automatically create a new thread in the concerts and gig board...
Here is everything !! And don't forget to say you added it in the calendar if you see the date in a new thread... Or if you create a thread THEN add the date in the calendar, say you added it but you couldn't wait until the approval to spread the good news !!!