Stupid question: I have installed the Simple Event Calendar plugin. But how do I put it on a page of my choice? Respectively, how can a plugin generally be integrated?

It's done.

Cheers!

No, not quite yet. At least not as I imagined it would be. Remaining with the example of the calendar: How can I integrate the calendar (or any other plugin) on an already existing page?

Cheers!

There are several ways how plugins may generate or interact with content

• Special Pages - whole plugin-generated pages (off-topic for this question). Example: SimpleBlog's blog page
• Gadgets - plugin generated areas. Normally Gadgets are not context sensitive and are used as Layout aeas (template-hardcoded and/or manageable via Layout Editor), but they can also be included into pages' content as 'File Include' sections. Themes have different amounts of 'slots' [1] where Layout areas can be inserted. Bootswatch themes only have the 'After Content' [2] area, which is automatically generated by Typesetter. Example: SimpleBlog's Categories and Archive Gadgets.
• Sections - plugin-based content sections, mostly used as part of page content but may also be used as Layout areas. Can only be edited WYSIWYG. Example: StickyNote
• DOM manipulation done by a plugin's JavaScript(s). I don't know an example plugin that does solely that.
• Filtering content, e.g. by using SectionToContent, Html_Output or or various other hooks

[1] Such slots can be defined in template.php using gpOutput::Get('Extra', 'Area-Name') for 'Extra Content', predefined settings.php-based Areas gpOutput::GetArea('Area-Id', 'Content'), or menus via gpOutput::Get('Menu');

[2] Plugins may also add content directly to this area via the GetContent_After hook.

How can I integrate the calendar (or any other plugin) on an already existing page?

The calendar is a Gadget (and the plugin also provides 2 Special Pages).
You can add the Gadget as 'File Include' section to the content of (single) pages or to an existing Layout area slot via Layout Editor.

It's these subtleties.... unfortunately, the documentation doesn't reveal much when it comes to embedding plugins. In general: Has it been thought about creating a more detailed documentation for Typesetter, a user manual? In any case, Jürgen, thanks for your quick and competent help!

Has it been thought about creating a more detailed documentation for Typesetter

Oh yes, it has been thought a thousand times.

Ok, seriosly.  I have started such thing about 1 year ago but it's still only a fraction of what it should be. Still needs some 100 hours at minimum before I can make it public.

Well, Typesetter turns out to be "simple & complex", I can imagine that the documentation takes a lot of time and knowledge. I hope the documentation is not a one-man project?

Well, Typesetter turns out to be "simple & complex"

Yep, basic usage is meant to be as easy as possible but there's quite a few stuff under the hood.