If you are a return player or new acc in neopet most prabably you will need to post slowly in the pc and other boards to make friends there and let people to be familiar with your username.
PC -Safe pet are pets that hang around and well known by the people in the PC so they are safe to be trade and won't cause you problems .
You could wait for rachel to tell you more in details as I'm not that good with explaining too xD