First prepare the picture to be used as a template, open PowerPoint and create a new blank PPT document.

View, master, slide master, enter master editing state. Click the Insert Picture button on the drawing toolbar, select the picture to be used as a template, and confirm.

And adjust the size of the image to match the size of the master. On the picture, the stacking order is placed at the bottom so that the picture cannot affect the editing of the master layout.

Now that we have created the template document we need, after exiting the master view, the next step is to save it.