My b2evolution Version: don't know
I have added a field in the table evo_blogs
it shows in the blog settings
it also shows on the blog
but it does not show in the admin tab write new posts
do I have to activate it or ... ?
how can I make also posts in these added blogs C, D, etc ?
Why would you add it to the evo_blogs table instead of adding a blog through the back office?
When you add a blog through the back office you will be able to set all the various blog parameters like "include in public blog list". Then you make a category for it and you can post in it.
You can find your version on any of your admin pages (back office). If it's old it'll be at the top. If it's newer it'll be at the bottom.
Hope it helps!