How To Cure Little Red Spot Which Looks Like Frostbite Back Of The Hand?

my friends wanted to see what really happens when you put salt on your skin, and then push an ice cube against the salt. I did this on the back of my hand. It appears to be a very minor frostbite. Im worried it will become affected, or it wont heal back to normal. It is a red spot and a little darker in the middle, and doesnt look to serious. It never really bothers me except if it gets hit against something hard, and sometimes it cramps. It just reminds me of a bruise, but i know it defintley is not. What should i di?