In most languages, you implement a stack using a dynamic array:
class Stack
items := empty array
function push(x)
append x to items
function pop()
return remove last element from items
function peek()
return items[length of items - 1]
function isEmpty()
return length of items = 0
In practice, use the built-in: C++ has stack, Python has list (use append and pop), Java has Stack or Deque.