I tried registering, but then it said my email address is already being used. Then when I tried to have my password sent to me, it said that my account has not been activated.

This means you registered your account, but you haven't activated your account. You need to click on the activation link we sent to your email box to activate your account. If you haven't received the activation link in your email box, you need to send your email, name, and phone number to violympic@moet.edu.vn for help.