New to Unity. Need kickstart.

I have taken on a project that requires updating some imagery in a Unity3D game. I have received all of the source code but I dont know a thing about Unity. I know iOS programming, Android programming and Windows Phone programming but I have never worked with Unity.

I have downloaded the ‘free’ version of Unity but I am thinking I probably should of got the free trial of pro. My goal is to eventually buy Unity and learn it but at the same time, I need to update these graphics fast.

I can open the project in Unity 3.5 and in Xcode 4.2 but cannot get it to run on the simulator or device. I also see a MonoDevelop Utility and there are some errors when building in Unity with some of the cs files.

Any tips/tricks would be appreciated. If I need to download the iOS version or pro to make this work left me know.

Thanks in advance.

YouTube, Google - loads of Tutorials on the subject.

Thanks for the quick responses.