Several things are happening here. First, if you are trying to create a file for Kindle you should be on the Amazon help page, not the iBookstore. Kindle uses its own format (a .mobi file) that you cannot get to directly from Pages. Go to their forum for help on the ways to upload your file to them.
If you are trying to create a file for the iBookstore, you can test it on your computer by opening it in Adobe Digital Editions (a free download) or (much better) loading your epub file onto an ipad. For a one-page document, if you check the box "use first page as cover" when you export from Pages, you will not see anything in Adobe Digital Editions. But, you really should test on an ipad, and don't forget to validate your file before uploading to the iBookstore.