Finding memory leaks will be much more difficult if it is done after the program is written. In the future design and write your program such that memory is allocated and freed appropriately. However you are learning a lot from this program so you will be better prepared in the future.

I think that if you search for every use of "new" and if you understand how the allocated object (pointer) is used you should be able to ensure that the object will be deleted sometime. It might not be easy to do but the person that wrote the program (you) would know best how difficult it will be.