Squats - 3 x 12 at 60-65% of you max
Hex bar deads - 3 x 7 weight that will be hard your last set
Lunges 2 x 20 each leg something lighter to start, get to know your body
Ham curls 3 x 12
glute ham raises - work the hams and lower back slowly, start without weight
then you can hold a plate while doing it
calf raises 3 x 12
stay away from extensions - really hard on knees, my opinion.