Hi,
Have you installed the full installation or custom one? Moreover, there is no Blog node in default installation in
Site manager -> Development section. Are you referring to the correct UI page? Haven't you meant the
Development -> Document types section instead?
You can try to install a fresh instance and a sample
Corporate site, where the Blogs section is properly configured.
As for the
Categories - you can assign the categories on the
Form tab (while creating the document) if you use
Multiple categories selector form control in the document type form, as mentioned in the note in
DevGuide article on assigning categories Regards,
Zdenek