Since Envira 1.8.0 you can now easily add a gallery to your page that will open the lightbox by clicking a link, an image or even an input button.
[envira-link id="381249"]Click me to view the lightbox![/envira-link]
Be sure to change the -381249 to match the gallery ID you have on your site for t! See the working example below! Also be sure to include a valid image src to the image you wish to use as your placeholder!Click me to view the lightbox!