I have halo 1 for PC and there is this level that is on chapter 7 and I think it is called keys to super weapons or something, its after you find out about the little round thing that flies that tried to kill everyone, anyway, the problem is that there is a locked door that I need to get past and I'm stuck.

Ohh that level, you have to go back to the oracle to unluck the door

Who's the oracle?

I have played Halo for X-Box; I believe the Oracle is that little round flying object that at a later point is controlling the little flying lasers.