First, 3.9.0 is however a good job from mem. Easy update - every thing works fine!

I can create categs for blogs, but they will never show anywhere. Ok, you can choose them in submission page.
Is there a way to show the categs on blogpage and sort the blogs?

Blog categories are shown in a block

And the Blogs are sorted in the categs?
Sorry mem, this the first time, that i've a look at blogs.

Of course, take a look here for an example, "Categorie"

http://www.scriptips.com

OK, i'v just create a main block, cause if you have much categs, it look a little bit better.