I took a data structure class and it was very easy. Don't let people fool you. Its so easy i dont even go to class. But to answer your question you are learning about the structures you can create with code youve learned. In fact you should have already covered several structures. If you are proficient at c++ and understand the concept of the structure it will be very easy. Your teach will most likely have you implement linked lists(single, or double, or circular), binary trees (including heaps and graphs) as well as hash functions.
Hope I helped! If youd like to see some code from my class feel free to PM me and ill send you some.
you will likely be asked to do a lot of pointer based structures. It would therefore be wise to make sure you understand pointers very well, and look ahead at the construct of a pointer to yourself...
foo* next; // <-- linked list construct base... a pointer to the type that you are...
those string together like
... code to allocate and stuff leading to:
x->next->next->next = something;
Obviously there is more to it, but if you can understand that much, you will be way ahead as it becomes a binary tree (left and right replace next) and if you go there, graphs (vectors of pointers to your type, uglyness!).