That does look bad, Honestly If you dont take care of that with a vet it is just going to turn into septicemia (blood poisoning) and will slowly die..
There is, however home treatment for fungus. It does require alot of patience though. And if it doesnt get better in a few weeks, then a vet will realy have to check it out, no excuse.
Anyways, Do you have all the basics down? UVB/UVA light, filter, water heater, proper sized enclosure, etc? If no, get everything you need ASAP. Turtles are not begginer pets and require alot of money and commitment. Just keep that in mind..
Anyway, here is the treatment for fungus:
www.austinsturtlepage.com go to the medical section, and click on "shell and skin problems" from there, find "fungus" and it will tell you what to do. Again, if this doesnt work..then a vet will be its only chance at life.
Good luck.