Can you be more specific in what you want exactly? If you want to change your page layout, you can change the setting on the specific page here:
With kind regards,
Bryan de Wit
The answer for you question is explained in this post if you haven't already seen it:
Mendix Forum - Questions (mendixcloud.com)
You have to create your own layout: Right click a folder in your module, Other and choose Layout.
Hope this helps.