2
Checklist first, so we can see if we're talking the same language
1. Have you created a new category first?
2. Created a forum for the category?
3. Gone to your new forum and there is no button for "New Topic"?
That should be all that is required...
edit: apart from giving webmasters permissions to start a new topic of course, which is handled through admin->newbb->forums-> [edit selected forum]- "Topic permissions for this Forum" ....