Making a hash table in C++

So I'm auditing a class in scheme, right, and one of the assignments (that I don't have to do, since I'm auditing) is to make a hash table in scheme for the purpose of calculating probabilities of bigrams and so forth. Now. I understand the basic concept behind a hash table, but I am not entirely sure how one would make one so that it was efficient (compared to an array of pointers, or something like that). I want to play around with it in C++, but I'm not sure how I'd go about building one, and it isn't mentioned in the books I have. Can one of you nerds give me some pointers?