Second key will not turn in the ignition?

First test, Try the key in the other locks on the car. Does it work in them? If it works in those try pushing the key in then gently pull it back while trying to turn it, it may be cut wrong or it might not fit your vehicle. If you cannot get it to work you will want to visit a dealership, normally if you can give them the VIN and prove that you own the car, they can get the code to cut a new one. A mobile locksmith can usually do that as well.