How Do Stacks Work?

Stack work on first in first out basis..
When we pop a stack it pop outs the top most value of a stack.
For example we have following stack
1
2
3
4
5
6
Now 1 is the top most value of the stack.. Now if we pop the stack, 1 which is the top most value will popped out of the stack and the stack will be
2
3
4
5
6
Now we push a value say 19
In case of push the value which need to be pushed will be placed at the top of stack. After pushing 19 the stack will be:
19
2
3
4
5
6
Hope it helps you!
Sorry for poor English:)