Your first step is to find a Realtor that you will trust and has experience with first time home buyers. There are many agents here from the Chicago area, and I am sure they will be getting back to you shortly.
That realtor will put you in touch with a reputable mortgage company that will qualify you for a loan so you know where you stand and how much your monthly payment will be. As first time homebuyers you may qualify for an FHA loan, which is a government insured loan that only required 3% down regardless of credit.
Also, even if you are working with an agent and still have questions, feel free to come back here and ask opinions... those are always free :-)
Good luck in your adventure in finding a home!!!