Hi C'
Pages creates two types of document: Word Processing, and Page Layout,
Yours is most likely a Word Processing document.
In word processing documents, page creation is automatic. A new page is created when needed to accomodate the added text. The old page and the new page are in the same Section of the document, and attempting to move the Page will actually move the whole section.
To move a single Page, you must first place that Page in a Section of its own, by inserting a section break before it and another Section break after it. You must also ensure that the place you will move it to is between two sections.
Usually, especially in documents that are mostly text, you would not move the Page, but would move the Content.
Select the text you want to move. Press command-X to cut that text from the document.
Click on the location you want to place the cut text. Press command-V to Paste it into the document at that location.
Pages will adjust the text twice—once to fill the space left when you made the cut, and again to make space for that text when you do the Paste.
Remember to check the spacing at the beginning and end of the pasted text, and at the location from which the text was cut, and make any adjustments needed.
Regards,
Barry