How can I open video in lightbox by clicking on button?

I have the button on the page "Watch How"

I want to open a Lightbox with embeded youtube video after button has been clicked.

I created a gallery with video and Lightbox enabled on the separate page and placed it in "not linked section"

Now trying to figure out how to trigger lighbox with video to open by clicking on the button.

My button is made with code:

<div class="watch-how-button">
<p>Watch How</p>
</div>

My Video ID is: yui317251501786830957615

I am following this tutorial:

https://answers.squarespace.com/questions/82227/button-that-pops-up-a-video-lightbox.html

I can't figure out how to:

Then, create a link anywhere you want with this updated to your video ID:

javascript:jqueryLightbox('yui317251501786830957615');

And how to link this to the button.

The script code was added to the code injection section.

Any help would be greatly appreciated. Thanks!

@ViktoriiaP If you're still stuck, this plugin will get it to work for you without fiddling with any code