Some basic clues.

First you need somewhere to store your data say a simple array and a variable to tell you which element in the array is currently top.

Now write two functions push() and pop().

To push or pop all you need to do is copy data into or out of the array and change the index variable. Also think about what should happen if you try to push too many values or pop more than you have pushed.

Not too difficult. Have a go and if you get stuck show us what you have. We are happy to help but you wont learn if one of us does it for you.