as the following subject.
From the menu select Format->Page and on the Page tab, make appropriate change(s) such as Orientation, size, etc.
Dialog from LO v4.4.7.2:PageSetUp.png
i don’t see it, just type of paper.
I have added a display from my system in my original answer. If you are using v5.1.x please note that the menus have been somewhat re-arranged and may be in a different location. Without that version I can’t tell you where it would be. To my knowledge there is no comprehensive list showing where items moved to. Best guess is Edit.
v5.1.1.3 menu selection is Format->Page/Slide Properties… and Orientation is listed under Paper Format.
In version 6.2.1.2 of DRAW, to change the orientation of the page from vertical to horizontal, select:
page, properties, then below the paper format options, select " orientation " button Landscape. You should immediately see the width and height of the page be updated.