Hi there, all the items on the menu card are created as posts and assigned to a category. If you’ve downloaded the demo content already, go to posts>categories and you’ll see the various categories for the menu like this – http://screencast.com/t/i3F49lWp7Tkb
To add to the menucard, simply create a new category for you posts, like “Salads” for example and save. Then go and create a new post, call it ‘chicken salad’ etc and assign it to the ‘salads’ category via the dropdown in wp post options.
Go into settings>general to check your homepage link is set up correctly. Also check in appearance > menus that the url for the homepage is set to your site url and not the demo, if it isn’t edit it and save.