C++ Problem using stacks

Please help! I'm stuck on how to solve this, Im having a hard time understanding stacks. I Have attatched the following pages for context, THANK YOU!

PROBLEM #1-First picture

Programming Problems 219 OGRAMMING PROBLEMS Using the class stack in the Standard Template Library, define and test the class OurStack that is derived from StackInterface, as given in Listing 6-1. The class stack has the following methods that you can use to define the methods for OurStack. L. / Default constructor /I Tests whether the stack is enpty stack): bool empty() const ItemType& top): void push(const ItemType& newEntry) void pop(): / Returns a reference to the top of the stack Adds newEntry to the top of the stack /I Removes the top of the stack To access stack, use the following include statement: #include Whenever you need a stack for any of the following problems, use the class OurStack that Progranning Problem 1 asks you to write Programming Problems 219 OGRAMMING PROBLEMS Using the class stack in the Standard Template Library, define and test the class OurStack that is derived from StackInterface, as given in Listing 6-1. The class stack has the following methods that you can use to define the methods for OurStack. L. / Default constructor /I Tests whether the stack is enpty stack): bool empty() const ItemType& top): void push(const ItemType& newEntry) void pop(): / Returns a reference to the top of the stack Adds newEntry to the top of the stack /I Removes the top of the stack To access stack, use the following include statement: #include Whenever you need a stack for any of the following problems, use the class OurStack that Progranning Problem 1 asks you to write