What do you mean by "where"? If you need your SIM card contacts to show on your phone's contacts list, you can open Contact/People app, go to Menu/Settings and an option similar to "Contacts to display". The exact operation depends on your phone.
Contacts are no longer stored on the sim card. You'll only find a few service numbers there these days. As Thacy said above, contacts should be in your device (and maybe backed up some place)...