[Hepatic]

PLEASE will someone put me out of my misery?

For the life of me i cannot understand how to get the following;

Champion of Challenges

Target another person's score on any Challenge and earn a higher grade than they did (Local QP+)

What the **** are grades? nothing is mentioned ANYWHERE in this game. I've beaten scores i've targetted but never trigger this as a result. Nothing i can find explains this, people seem to just luck in to getting it and its ****ing me right off!!

TIA