I have not noticed it so keenly till now, what is a Set under the account “My Set”, what is the difference between a Set and a Team.
In a set, you can add people who are your friends or classmates or whatever you just need their username and compare your performance. But a team is built for participating in any contest(s). A set keeps all people together so that you can keep an eye on their ratings and performance in any contest(s).
You can form sets to add programmers, anyone on codechef, might be friends, relative, enemy or your inspiration! Sets are kept private, only you can see them.
This is how I organize my sets.
Create and organise your sets at www.codechef.com/sets
If my memory serves right, it has been asked before. Please try searching forums first so we can avoid duplicate Q the max we can