ok, I found out
1) go into calendar/page_types and copy calendar_event.php
2) paste into your theme folder where the other page types are (like full, right_sidebar etc..)

Start adding your own stuff (header , footer etc...

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Would be helpful if every add on developer would commit to filling out some kind of a structure diagram with the location of all used components, and add that as default file. Takes a couple of minutes to do that.
Maybe C5 could provide one for all?
This is all relative easy stuff, but as a beginner it takes quite some time to figure it out.

Thanks.

Is this a theme you downloaded from the Marketplace? if so, which one was it? I'd like to take a look at it.

It sounds like the theme's author may not have set up default.php (which gets used when there's no page type defined) properly. It should at least load the editing toolbar and any other standard components of the theme (css, header, footer, etc).

Hi Matt,

Thanks for replying.
It seems to work fine with the plain yoghurt theme.
I'm using a custom theme that also has a default.php but I guess something in there is not working correctly. I'll have an other look at that.

One other thing:
How can I edit the title of an existing event?

Thanks.

ah, got it.
It's in the properties section of the page.