mobile

I made the mistake of trying to flash a custom ROM to my phone without really knowing what I'm doing. I was following these instructions (http://www.slimroms.net/index.php/installation) and when I was in the TWRP menu it gave an error when I tried to wipe (I don't remember what it said) but when I went to reboot it said I had no OS installed. I tried to follow these instructions (http://forum.xda-developers.com/show....php?t=2253666) to fix it using odin but to no avail. I get an error in odin

Now if I try to boot into recovery I get an error about my firmware that says "s3 firmware upgrade encountered an issue please select recovery mode in kies ". I am totally lost and afraid I dug myself into a hole I can't get out of. Any help at all would be appreciated.

Not really sure if this is the right area to post but my phone is i747m galaxy s3 and I'm with Koodo mobile.