Permissions for the Blog can be found in the standard usergroup permission page, the default install attempts to create a set of permissions that are based on the permission to create new threads / posts.

When adding / editing a usergroup at Usergroups > Usergroup Manager > Edit Usergroup in the right column you will find the following permissions:

The other permissions are self explanatory and are closely linked to their Thread / Post counterparts which can be read at this manual entry.
User Contributed Notes: Permissions