The best thing to done, is get a piece of A4 paper and fold it, depending if it is landscape or portrait, this will give you the open edge. Treat it like you would a book, so draw out your layout on it, then open it out and it will show you how it needs to be positioned. Everything should be normal for reading, except if the layout is landscape, then the back will need to be upside down.
Yeah you will need to send to print with some of the artwork 'upside down'. Do a quick sketch to replicate the design on a blank piece of paper to realise which bit will need to go upside down. It's most likely going to be one half of one side.