If a page designer can create his own template therefore I might say that he is professional in lay-outing. If you want to create a 6 x 9 template ".qxp" file here are my step by steps for you.
First open QuarkXpress of any version you are using. (mine version: QuarkXpress 10) You can download this on www.piratebay.com via uTorrent 3.3.1.
Select Project... or simply use Ctrl+N. (Click image to enlarge)
Fill in the layout name, sizes, margins, gutter and then OK. Always set the variables right most especially the width and height. And since this template is for interior book design. Facing pages, Allow odd pages on left and automatic text box should be check. (Click image to enlarge)
Sample of our created 6 x 9 template.
Now you can create any other book sizes just following the steps above.