In "Starting out with C$++$ from control structures through objects, $10$th edition", programming challenge $2.$ Test scores #$1$

It wants me to dynamically allocate memory for an array. I$\text{'}$m confused about defining the array with an initial size. Do I just define the array as usual using the size I will also be using for memory allocation? If I prompt the user I still don't understand how I would define the array.