Create Or Edit Master Page. From there you can edit the slide. Click on that link and you will see this dialogue box.
On the Format menu point to Page Layout and then click New Master Page. Click a slide master or layout. Go to All Files _catalogs masterpage THEMENAME.
This directory is the folder containing Master Page and Page Layouts as well as.
Tap the thumbnail again then tap Edit Master Page. The Design Manager is not activated by default in SharePoint 20132016 Or in Office 365. To create a new master page you duplicate an existing master page name it then modify it. Click Close Master Page to go back to publication view.
