There were two people and only one went in and stole items what happens if the person who stayed outside confesses to being there.
Federal Crime Lawyer
If by "went in" you mean a residence, then all of you could face charges and conviction of residential burglary. I does not matter that you never entered and took anything. If you did anything to help out and had knowledge of what the others were doing inside, then you may have criminal liability. By helping out, I mean planning, driving, providing a car or other tools, acting as a look-out, etc.. You need a lawyer and should not submit to police questioning without an attorney.
The maximum penalty for trespassing is 180 days in county jail, and probation. A stay away order is also likely. Also, a misdemeanor conviction will be on your record, until it is expunged. See California Penal Code section 555.
The remainder of your question involves other charges that carry much stiffer penalties. Depending on the facts, this case could be charged as a felony. I strongly advise you to speak with an attorney immediately. When is your arraignment date?
The above is not legal advice, and should not supplement actual legal advice from an attorney with whom you have an attorney-client relationship with.