Can someone direct me to the part of the documentation/wiki oder a forum entry where I can get help concerning a multilingual site.
I played a little with the demo and was able to translate a page which is nicely solved but I have no idea how to com to the translated site from the user perpective or how to switch/choose the language from a users view.

I actually can surf to the translated page by entering the url but I wonder if different language versions of the same page are somehow connected.

There is currently no built in way to show if other translations exist on your website. If you build one yourself you could attach it to Ticket #1889.

I'm having trouble creating translations in the CMS. But if you look at the database of a working site it should be easy to figure out what is going on. I guess SiteTree_lang.OriginalLangID refers to a SiteTree.ID.