No posting from up front. The back office is designed for all your "administrative" stuff, and adding content is basically administrative. The front end - what your visitors see - is stuff made for public consumption. Some stuff up front is for logged in people to see (a link to the admin section, a link to your own profile), but these amount to links TO the back office so you can do your 'behind the scenes' work.

Think about it this way: where on the front page would you put all the stuff you need to make a post? Textarea for writing is one. Blog selection, category selection, toolbars, if it's published or a draft, if comments are open or not, and what plugin renderers you want applied to this post. It takes up a page full, and it's not something visitors would be needing.

So with one click from the front you're in the secret door that leads to the halls of administration for your particular empire ... er ... domain.

May I add to this:
If you assingn a blogger and not a second admin he will have limited rights and he will see only part of the backoffice, in fact only the 'write a post' section.
Due to cookie issues you can only test that in a different (brand) browser or on a different computer. Assign a new blogger and try to write a post. Try it.

The edit link is a good example of what you can see but visitors can't.

Good luck

*spam crap removed