CC is short for counter-conditioning: conditioning a dog against their negative, undesired attitudes about a particular thing using positive reinforcement. For instance, if your dog is afraid of bikes (which does happen!), you may want to spend time feeding them treats and rewarding them around bikes until the presence of the bike (because of the positive association of the bike with food) evokes feelings of happiness and eagerness from the dog rather than fear and aggression.
Yes, counter-conditioning to the crate is pretty straightforward--feed all the meals in the crate, give him a treat in the crate and slowly start closing the door for longer and longer periods. Never let him get uncomfortable and feel trapped in the crate. If you explain what problems you are having with the leash training, we could give you some ideas how to deal with that.
If puppies are not used to the leash sometimes very, very, very small steps need to be taken, like starting with something light (a yarn) tied to their collar, getting them used to liking the leash in your hand (not clipped to them), dragging it across their neck, down their back, etc.