So ...

Upon activation, you won't find any new menu items in your Wordpress admin area. In other words, there are no settings to configure.

Simply create or edit a page/post and place your cusrsor in the exact place where you want to show the before and after image.

Then click the newly added "Add Twenty20" button above the text editor:

A pop-up window will appear allowing you to select two images from your media library:

Once the images are selected, simply click the "Insert" button.

Next, you'll see a new window with text fields that will allow you add content on top of the before and after photos. Also, you'll be able to define the slider direction, the width for the slider, etc:

And that's it ... Once you are happy with your choices, click the "Insert Shortcode" button to add the before & after photo in your post/page.

OK. Now let's see the result ...