So can anyone tell me how to make Infinite Autoplay in Image Slider? Let's say there are 4 Photos. In Every 2 Seconds, It should change to the next Photo

I ==2000ms==> II ==2000ms==> III ==2000ms==> IV ==2000ms==> I

Note: I don't need already written code, I just want a simple "algorithm explanation" about that situation(I don't know any Javascript libraries for sadly)