Select the Insert section then select More Gadgets.
Open up the Insert menu in the Google Sites Editor You should be able to see a list of available gadgets you can install on your site, including Tables, Links, and Images Select More Gadgets. This will allow you to add customizable tools like POWr Event Gallery to your site.
Copy and Paste URL
You will see the Gadget manager. Choose Add Gadget by URL. Then paste this URL into the field. Select Add to finish.
After you add your new Event Gallery Widget to your page, you're probably going to want to adjust the shape and size of your Widget. Using the options in the pop-up window, choose the height and width of your plugin. We don't recommend it, but you can insert a scrollbar, title or border to your Event Gallery Widget. You’ll have more editing controls directly through the plugin.
Set up POWr Event Gallery
Visit the live Google Sites web page and select the gear icon in the upper right corner of your Event Gallery Widget.
In the POWr Editor, click Import Existing Event Gallery, find Event Gallery- and click Copy.