This sounds like school assignment. The differences are not that great. We do not support school work here.

This page has examples of both. N ote the "POSIX" section is not all that big:
IPC:Shared Memory
Read the one paragraph on POSIX. Use all of the rest of the examples, change open() calls to shm_open() and close() to shm_unlink(). And there you are.
system V -> POSIX.