In this step, we’ll make the slider bar, a horizontal rectangle that will be sort of the "track" of our slider control (which we’ll create later on).
To start, use the Rectangle Tool (U) and draw a rectangle like on the image below. Make sure that the Rectangle Tool is set to Shape layers mode (you can set this at the Options bar at the top). For the Color of the shape, use a gray color (#dddddd) — you can also set the Color of your shape at the Options bar.