Free software, I've never used any, but peeps recommend Gimp, Picassa, and Corel Snapfire.
You need some edit software, but, you need to try alter your approach imo.
Shoot a good photo and use edit software to enhance it.
Don't use software to save a poor shot unless you absolutely have to, where is the incentive to take better shots if your gonna use software as a crutch.
Get focused, If your leaving the house to shoot night shots, you have to make the effort to carry a tripod, its almost as neccesary as the damn camera itself.
You could do allsorts with this photo, non of it better than shooting a crisp well exposed shot first time round...if its not sharp, you cant make it sharp afterwards..