Can you post articles from the frontpage?

The answers is, yes. But to be able to do so, you will need to have the login module and the submit article link show in your template. The login should automatically be there when you install Joomla, but you might have removed it at one point. If so, look under Extensions > Module Manager to locate the related module. Its name is mod_login. This module is necessary because unless you are logged in from the frontpage of your site, you will not be able to publish and article.

You should have your settings in such a way that once logged in, user levels for which you have provided the option should see a user menu. Under this user menu, you will need to have the Submit Article link. If for some reason you don't have this, don't worry. You can just create a new one. In your administration backend, go to Menus. From there, go to the User Menu. Then click on the green New button to create a new menu item. From there, select Articles > Article > Article Submission Layout. The ability to submit articles will only work for user levels Author and above. So even if you were to make the related link public, only you and people you have designated as authors and above will be able to make use of it.