The first thing to do is to get a full set of water test results. Depending on what the test results are there are various things that might need adjusting. The only thing we can say for sure is that you are going to need some CYA/stabilizer/conditioner.
Everything will be much simpler if you purchase a top quality test kit. I recommend the TF100 from TFTestKits.net. The Taylor K-2006 is also good. But you could get away with a combination of a cheap WalMart six way drop kit and some pool store testing, at least for a while.
Until you get your test results and start adding CYA, you should add 2 ppm of chlorine each evening. If your pool is 10 feet across and round, and the water is 30 inches deep then it holds about 1,500 gallons. 2 ppm of chlorine in 1,500 gallons is just about 6 oz of household bleach if the bleach is 6% (check the label, some of them are much weaker).