1. Put the images on a separate page and publish your site.
2. Go to that page and right click on the image - get the image URL.
3. Drag a widget element to the page where you want the image with the "pin it" option.
4. Make it into an HTML widget - make sure it's large enough for the image
5. Paste this code, replacing the highlighted image URL accordingly:
<a href="//www.pinterest.com/pin/create/button/" data-pin-do="buttonBookmark" ><img src="//assets.pinterest.com/images/pidgets/pinit_fg_en_rect_gray_20.png" /></a>