I am doing a simple web page where the goal is to graphically represent a stack operation.

For example, a store shelf where items (all of the same type) are only removed and replaced from the front. In other words, it mimics a simple LIFO stack. At times the items may need to be sorted.

I understand how to push and pop, but what's the best way to represent the stack functions on the screen for the user?
Thanks for any tips!
SC