Choose Insert, then More Gadgets.
In the Google Sites Editor, open the Insert menu. You should see a list of available components and gadgets you can add to your site, like Images, Links, and Tables. Find and select the More Gadgets option. This will let you add editable tools like POWr PowerPoint Embed to your site.
Paste in URL
You will see the Gadget manager. Choose Add Gadget by URL. Then add this exact URL into the field. Click on Add to finish.
Change Height and Width
Now that you have embedded your new, fully customizable PowerPoint Embed Widget onto your website, you'll probably want to change the shape and size of the Widget. Use the options in the pop-up to choose a height and width for your plugin. You can decide to create a title, scrollbar or title around your PowerPoint Embed Widget, but we advise against it. There is more editing control through the plugin itself.
Set up POWr PowerPoint Embed
Go to your live Google Sites website and click the Settings Icon in the upper right corner of the PowerPoint Embed Widget.
In the POWr Editor, click Import Existing PowerPoint Embed, find PowerPoint Embed- and click Copy.