So ...

Upon activation, you'll notice a new "Modal Login" menu item in your Wordpress admin menu.

It will take you to a simple configuration page where you can define/customize the actual modal login form.

As a first step you'll have to select a modal login box type:

Next, you can scroll down to manage the login/logout redirects for the form:

Additionally, you can also allow users to generate their own passwords.

Finally, you'll have to scroll down to the "Style" section to define the background color, button color, link color, etc:

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