Lighting is everything, or at least until you realize that there are at least 10 more things that are everything.
I realize that this is not a "portrait session" but it's not even a good snapshot. There are probably hundreds of primers for portrait photography which you can look at to make sure that you get a better picture next time. All of them will teach you that you broke almost every rule, each of which would have made her look a lot better and would have made you a lot happier.
I'll start with few important tips:
1) Everything that isn't her in this frame shouldn't be there. If you turned your camera and had her stand further from the wall, using a shallow depth of field, everything else wouldn't be there. Photography is a subtractive art form. You need to get rid of everything that isn't important to the picture.
2) Go get some electrical tape and tape down the on-board flash, or disable it, or rip it off. I'm sure there are uses for it (Actually I'm not sure at all. Someone here will correct me) but I have never been left wanting. The really expensive cameras don't even have them. You could have bumped up the ISO, shot at f4, and made sure that everyone stayed very still. The shot would have been 100 times improved.
3) The other 100 things, but those first two would be most helpful.