Until you get some cya in there, you're not going to be able to keep any chlorine in your pool. You can buy some cya (also called cyanuric acid, isocyanuric acid, stabilizer or conditioner) at a pool store and add enough per package directions to get to an intial reading of about 30-35. It takes awhile to dissolve so after you add it, wait a week before testing for it or adding more or else you may end up with more in there than you want. You can either add it slowly to your skimmer while the pump is running or put it in an old sock and hang it in front of a return jet or set the sock in the skimmer. (If you do add it directly to the skimmer, like I do, do not backwash until it dissolves or else you will just be throwing it right out.)

Until you begin to get a cya reading, you'll probably need to test your pool at least twice per day and each time add bleach. After you get your pool cleared and get some cya in there, you'll be able to just test it and dose it in the evenings.

I would also suggest raising your ph a little with some borax.