Here are a few good leg exercises:

Quads:
SQUATS, front squats, hack squats, db squats
leg press
leg extentions
lunges

Hamstrings:
lying leg curls
standing leg curls
seated leg curls
stiff legged deadlifts

Calves:
standing calf raises
seated calf raises
donkey calf raises

Pick 2-3 quad exercises (SQUAT), 1-2 hamstring exercises and 1-2 calf exercise and start training them hard.