I have just created a blog and want to add some menus. The only one I have at the moment is the home one.
You misunderstand. The entire menu bar is the menu and you can include as many menu items as you wish in the custom menu.
Among the most common misconceptions is that bloggers fail to understand that the static pages http://en.support.wordpress.com/pages/ they create do not automatically update. Only the dynamic pages like Categories, Tags and Archives created by the software when we publish a post we that we have assigned Categories and Tags too will update automatically update with posts.
By default the front page of the blog is the post that displays all posts in your blog. Though there is only one dynamic page in a blog for posts (not pages) http://en.support.wordpress.com/post-vs-page/ and we cannot post to more than that one page. we can create the appearance that we have posted to more than one page.
We organize posts by assigning categories to them. You can create a custom menu and add the dynamic categories pages into the custom menu.
Here’s a link to a custom menu walk-through > http://onecoolsitebloggingtips.com/2011/08/11/wordpress-com-custom-menu-walk-through/
There are many common errors, misunderstandings and misconceptions when creating custom menus and you can read about them here. > http://wpbtips.wordpress.com/2011/12/19/custom-menus/