Need some help! iMac won't boot

HELP!! Problem with 27"iMac. Disk utility can't repair disk
I came home from vacation and my iMac was locked on the screen saver. I held the power button down to turn it off and now it wants me to set up computer again. I tried to repair disk first, but it's says disk utility can't repair this disk. Back up as many files as possible, reformat disk, and restore your backed up files. I am new to Mac and don't know how to back up the files while I am on this screen. I just need to back up some pictures that I recently loaded into iPhoto. Can someone point me in the right direction?

Another bad thing is that I never setup time machine. Can I still back up my photos and iTunes account?

 

Apple store isn't an option. Closest one to me is 5 hours away.

So if I download disk warrior on my PC laptop and make a disk of it, I can then take it to my mac and boot from it?

My mac is telling me to back up as much as I can now, but how can i do that with the screen I am getting?

I have an external 2TB hard drive that I back up to manually every once in a while, but I haven't done it in a couple of months. I have a lot of pictures and itunes movies imported since then.