Sounds like you are trying to make a four page booklet and har having difficulty with the imposition part of the process.
Facing Pages in Pages sets up the document to produce odd-numbered pages formatted to be on the right side of an open book and the even numbered pages to be on the left side, when the document is shown on a one-faced screen, where every pair of pages can be placed as if they were the 'middle pages' of the book
But even in the simplest example of this type, a four page booklet, printed on both sides of the same sheet, then folded in half needs to have half of the even numbered page on the Right and the other half on the left, depending whether the page is on the inside or the outside when the sheet is folded.
The process of resorting the pages is called imposition, and there are several applications available in the Mac App store, some of them free, others with in app purchases, and others that have an up front price.
For your case—a single sheet booklet folded once to make four pages—is simple enough to handle 'manually' and print at home.
I'd suggest using a Pages Page Layout document for this task, rather than a Word processing document, and starting with the Vertical Photo Card template.
Depending on your region, this template will have two 'pages' sized to fit on either a US Letter or A4 sheet.
The image is from the page thumbnail page images sidebar.
The outside pages—Page 4 on the left with only a small text box, and Page 1 on the right, with a photo (and other graphics) and some text in a text box.
The inside pages—Page 2 on the left, with only a small text box (intended to be deleted before printing the 'card') and Page 3 on the right containing two text boxes and a graphic object.
Depending on the type of content you want on each page, you may want to replace one or more of the image containers or text boxes currently on the pages to accomodate your content.
Printing: Most printers capable of duplex printing will have a menu choice in the Print dialogue letting you choose the spine orientation—parallel to the long or short edge of the 'page'.
One setting will give you a result resembling a scenic wall calendar on which each page has a calendar on the front with its bottom row closer to the floor than the ceiling and a scenic photograph on the back whose bottom is closer to the ceiling until that page is turned up to reveal the next month and the now upright scene on the back of the previous month.
The other setting is for a book (or booklet) that opens left to right.
Start with a single copy printing to test which setting is right for your job (my last printing of this type of document was long enough ago that I don'r remember which was needed on my printer.)
IF your printer does not support duplex printing, you'll need to run the paper through the printer twice; once to print the outside pages, then again to print the inside pages.
As above, print a single test copy to determine how you need to place the paper into the printer tray in oder to have the twi sides come out as you want them.
I usually have my thumb on top of the stack of paper I put into the tray, so fo my test, I put a small pencil dot on the paper where my thumb was, then close the tray and print one copy of the first side.
Examine the result to determine where your thumb was in relation to the printed page and decide where you need to place your thumb when returning it to the tray for the second run.
Draw a circle or number 2 at that location, place the paper in the tray with the new marker in the same location as the dot was for the first run, and print one copy of the second page.
If you are correct, the print should be upright on all four pages of your folded booklet and you can go ahead with the full print run. If not, reexamine to determine where you went wrong male adjustments and test again.
Regards,
Barry
