If you wish to build quads,and associated leg muscles that hold body weigh in suspension, there are a number of "home" exercises you can do.
1. try "half squats"..slowly lower your self down bending your knees to half-way (don't go down all the way, not good for the knees), hold, slowly lift up...do this 5-10X, 30 seconds break and repeat. if you can do so, 1 or 2 more sets of the 5-10X repetitions, then give your self a day off, then repeat the exercise. after 1 to 2 weeks add either more repetitions to your routine, or add weight in your arms, even a weight bar, or both. try 5 or 10 lbs extra at first, and see how it goes.
2. to add strength to your calf muscles (and you likely will need this too) the simplest thing is to stand with your toes+balls of the feet on a stairs, or anything where your heels are well of the ground (brace yourself on the handrails, don't take much weight in your hands)then dip your heels down , and lift yourself up with your calf muscles..do 5 -10 X, and do 2 to 3 sets of these repetitions.
3.If you need more "core" strength,to include the "back-side" then try this..lay flat on the floor face-up, put your legs together and lift up both legs (keep them straight for maximum effect). only lift them 2-4" off the floor,hold, and you will see how many muscles that will work.
If for any reason you have difficulty lifting both your legs, bend them at the knee, and try that for a while.
There are many many more variations for this, but do those for a few weeks (every other day is best for the exercise to work, and not injure yourself) and you should feel the difference! It can be difficult at first, but it will pay off...good luck and don't forget to stretch! preferable before and after...these have worked well for me, especially before I found a gym with the right equipment...