I think theres a bunch of programs you can do that are free, your trying to improve leg stregnth right?
1 do a 5x5 program on squats for a couple months great for beginers
2 Do ws4sb3 great for all athletes but its a complete program for your upper body as well its from Defranco he trained 100s of pro athletes.
DeFranco's Training - Articles
3 Smolov jr. Only try this if you are pretty experienced with squats, its a lot of volume. I would recomend using box squats instead of normal back squats so you wont be too sore.
Iron forums - Official Smolov Jr Bench/Deadlift Thread /w Information &