Virtual Judge is not a real online judge. It can grab problems from other regular online judges and simulate submissions to other online judges. It aims to enable holding contests when you don't have the test data.
Problem Set is the place where you can find large amount of problems from different programming contests.
Online Judge System allows you to test your solution for every problem.
If you want to join WUST ACM CLUB, you can contact：firstname.lastname@example.org.