With sliders you're able to add multiple photos on one place. It'll automatically rotate through a series of photos.
If you want to add sliders in the Visual Mode you can click on "Slider" in the right rail. Now you'll go to a screen where you can upload a photo to the Slider. Upload a photo or choose one. At the end you can change the settings of the slider.
You can use the following code to add a slider:
<gallery type="slider" orientation="bottom"> Photo.png|Describing|link=Link Here|linktext=Details </gallery>