Write comments for C/C++ code so that it is easy to understand

Write comments for C/C++ code so that it is easy to understand . The code has already been completed and runs perfectly. The code is not too long. I need more comments for the parts where pointers and stuctures have been used in particular. The code can be provided to you if you think you can do the task within 12 hours. The task, to which the code applies, will also be provided to you