...
Click on a slide you’ve created from a template to view it.
If the side drawer isn’t open, click the details button
to open it.:
Click Copy to my library.
Give your slide a short, friendly name and click Create.
...
Click Add slide at the top-right of the slide sorter to open the side drawer.
Scroll the drawer down to the My Slide Library section.
(Optionally) Preview your slide by clicking on its thumbnail in the drawer, then click Done.
Click the drag handle
of the slide you want to use, and drag-and-drop it where you want it.:
The slide will pop open ready for any editing you may want to do, then click Done.
...