adding a 'Add a Post' button to menu

I am sure this is a super basic thing that I am just missing. I have tried several searches & themes but no luck.

I would like to have a button on my menu bar that would bring you directly to the ‘add new post’ system. Ideally this would prompt you to login if you are not already.

I know that I can use the standard choices in the wordpress theme (I am currently using twenty eleven) to login and then the new -> post but I would like to make it more direct.

Thanks
Andy