How To CODE that Allow Users to Select Multiple Sliders?

Hello,
I am a beginner PHP and WP Coder.

I have seen it many premium themes and want to achieve that myself.

I want to allow users to select the sliders (FREE ones) that they would like to use from a settings page in the admin.

For eg: If someone wants to use BX slider, he selects it from the drop down I make.

Then if he wants to change it to JS slider he just selects it from the drop down and voila.

Is their any tutorial for it or can anybody give me any direction ?

Thank you