The preferred option by the moderators is to post a screen shot. To do this see the links in my signature.
If you really feel it is necessary to post the file then go to a free file hosting site like Box.com (remember to mark it for sharing) then post the link it provides in the thread.
Just remember that some posters either won't or can't (because of security) download files and so you will be restricting how many people look at your file.