Is it possible to add advertisement or banners in a normal slider made of posts and pages in Smooth Slider?

Yes, one can insert images with link and description as per his/her choice without writing a separate post for that purpose. Which means it is possible to insert advertisement or banner in the Slider. To do that, you just need to upload the banner of proper size to media library and add that image to the slider. Provide proper description and title and also provide the target URL (may be the affiliate URL). Checkout the screenshots provided below.