How to start with shared folders

[Thomas Luft]

Hi there,

I am new to Kolab an installed the server about 3 weeks ago. So far 
everything is working, however I can't create shared folders. Every time 
I do the webadmin interface complains about missing information 
(screenshot here: 
https://kolab.postapotheke.biz/owncloud/public.php?service=files&t=8a1a39ff1fe25a4f708f696a381d982c)
As you can see I use the German localisation and maybe this is the 
problem? However I don't know how to switch Kolab to Englisch?!

If you have any idea you are very welcome.

Kind regards

Thomas