While a GC holder, you can marry a visitor, but she cannot legally remain in the US and certainly cannot work. You would file for her GC as the spouse of a LPR. She would need to leave the US and return only once she receives her GC. Check the visa Bulletin each month for the current priority date. It is now about 2 years but that varies widely.
Be advised that an illegal overstay will not be able to adjust status as the spouse of a LPR. She can only work once she has authorization.
If she qualifies for an H1B or L1 visa, she may have her employer sponsor her in the interim. If no, she needs to expect to go home and wait. Illegally present foreign nationals are subject to detention and deportation.