Don't panic, it doesn't look that bad. Use some warm, soapy water and a cloth to clean the wound and surrounding area. Then, apply some antibiotic ointment (with no "caine/cain" ingredients) to the wound. Before you re-introduce the chick, it would be best if you disguised the wound with some sort of wound/disinfectant spray, like Bluekote--otherwise, the other chicks may peck at the red.
I'd watch the chick carefully for the next few days, for any signs of infection (swelling, discharge, etc.), and make sure it doesn't get picked on. However, it should recover fine.
Looks like it is not actively bleeding. If you have bluekote spray the area to keep others from pecking. If you don't ( and I didn't when mine were small) try blotting with hydrogen peroxide - it masks the blood.
I'm not trying to be critical, but this chick looks too young to move to a tractor. Keep her/him in a protected environment til this resolves.
Fortunately, it doesn't look like a bad cut. I'd make sure that it is clean, using some warm water. Next, put some antibiotic ointment on. Don't use antibiotic ointment with any "caine" ingredients or painkillers, as these can be deadly to chickens.
Make sure to keep her separate from the other birds until this heals. Birds will peck at blood and red color, and she could be injured more.