After pressing the "Create New Slider" button you will reach a form where you are asked to enter a Slider Title (used for the Slider overview in this backend) and a Slider Alias (a slug that is used to implement the Slider in your WP later, so keep it simple with no spaces and special chars).
You are also prompted to enter the Sliders Basic Settings, a Slider Title (for you to remember the Slider by) and a Slider Alias (please do not use special characters or spaces here, this defines the shortcode for you to use in your content).
The options in the boxes on the right side (General Settings, Position, Appearance, Navigation, Thumbnails) have helping Tooltips on mouseover so they are not explained here.
The Slider Type can be fixed (not responsive, fix dimensions), responsive (changes depending on the size of its max. sizes given later in relation to the screen size) or fullwidth (always 100% in width of the screen size, but height keeping the aspect ratio).
The Sizes section is needed to fit the slider in all screen sizes needed. The height of the slider will always be calculated to keep the aspect ratio from the max width and height given in the Slider Size line.