There are many ways to achieve what you want. The very simplest is to design your slider as part of the second section, then up it a bit with Top. See the video below:
In any case, the slider has to be a floating element, so it has to be part of the first or second section and flot up or down. If you run into positionning trouble you can also use Absolute to position it. But as far as this method works, keep it.