Choose Insert, and then More Gadgets.
In the Google Sites Editor, find the Insert menu, and open it. You should be able to see a list of available gadgets you can install on your site, including Tables, Links, and Images Find and select the More Gadgets option. This lets you add editable tools such as the POWr Graph to your page.
Copy and Paste
The Gadget manager will appear. Click on Add Gadget by URL. Then add this exact URL into the field. Select Add to finish.
Adjust Height and Width
Now that you’ve added your new, customizable Graph Widget to your Google Sites page, you’ll probably want to adjust the size and shape of the Widget. Using the options in the pop-up window, choose the height and width of your plugin. You can decide to create a title, scrollbar or title around your Graph Widget, but we advise against it. You'll have more control while editing right through the plugin itself.
Set up POWr Graph
Go to the live Google Sites website and click the gear icon in the upper right corner of the Graph Widget.
In the POWr Editor, click Import Existing Graph, find Graph- and click Copy.