Choose Insert, and then More Gadgets.
In the Google Sites Editor, open the Insert menu. You should be able to see a list of available gadgets you can install on your site, including Tables, Links, and Images Find the More Gadgets option, and click it. This will let you add editable tools like POWr Vimeo Gallery to your site.
Paste in URL
You will see the Gadget manager. Click on Add Gadget by URL. Then copy and paste this exact URL into the box. Click on Add to finish.
Change Height and Width
Now that you have embedded your new, fully customizable Vimeo Gallery Widget onto your website, you'll probably want to change the shape and size of the Widget. Using the options in the pop-up window, choose the height and width of your plugin. You can also choose to add a border, scrollbar, or title around your Vimeo Gallery Widget, but we don’t recommend it. There is more editing control through the plugin itself.
Set up POWr Vimeo Gallery
Go to the live Google Sites web page and click the Settings Icon in the upper right corner of your Vimeo Gallery Widget.
In the POWr Editor, click Import Existing Vimeo Gallery, find Vimeo Gallery- and click Copy.