To create a new slider you have 2 options. Create a slider from scratch, or use an existing (demo) one as a base. In this article we will introduce the first option, and you can read about the second one in the following article.
On your Joomla backend navigate to Components/Layer Slider page. After that click on the Add new button, you need to add your slider's name. Then the slider settings view will load. As you can see there are many configurable option which detailed description can be found in Slider settings section, started with the Layout configuration. Now use the default settings, and click on the Slides button on the top.
Now another view loaded, where you can see the slide settings. As you can see it can be separated into 3 parts:
Detailed documentation can be found for Slide settings and Layer settings as well. So now you are able to add a background image or even place content by add a new layer. You can also add new blank slides and duplicate the current one if you only would like to make slight changes only.
When you are ready, don't forget to click on the Save button.