Try reflective listening.
Eg, "I can see you are really disappointed (sad, angry etc) you didn't get the red hoop, but the blue hoop is a great colour too".
Help him to understand these feelings are normal and show him it's ok.
I tell stories to my kids about when I was little or when I was feeling a certain way. They are comforted by the fact they aren't alone.
My two react really differently to certain things.
I remember a time my son was playing poison ball for the first time with a group of children much older than him. I was watching and could tell he had no idea what was going on or what was about to happen. He was a good target for the kids and he was the first one out after being sconned by the ball in seconds.
I went to run to his side to comfort him. He was trying so hard to fight the tears and looked really sad. A very wise mum next to me stopped me and said, "leave him to work it out, he needs to learn to deal with disappointment." I watched him take a big breath and watch the rest of the game. The very next time they played he knew what to do and even though he still got out the 3rd or 4th time he dealt with it with confidence.