You might also tell us what a "courier management service" is. What are the problems you are trying to solve? What do couriers do and why would you need to manage them, and why would the management of couriers make a good service? And "service" is a very much overloaded word; what kind of service did you mean? Give us some detailed requirements or examples!
But most likely what you are asking for is too big or too general. We are happy to help you solve a specific coding issue. We are less likely to provide designs or architectures for entire applications, which is what it appears you are asking for. After all, many of us make our living by creating such designs and we are paid well to do it. If you feel that the scope of the design is beyond what you are capable of, then hire someone to do it. (Of course if you were hired to do this then you are in deep do-do...)
However, if this an assignment for a class you are taking, then you need to do it yourself. Otherwise how else will you learn? Making mistakes (while in school) and learning from them is a good thing (I cringe when I look at some of the code I wrote way back then!). But giving up and wanting others to solve the problem for you is not a good thing.