Hi
If you have pool with pump and skimmer you only need to buy some 4 in one chlorine tables and just put one in the skimmer basket,normally1 a week dpending on use and weather, in this heat you will use more.
If you dont have a skimmer in the side wall you can buy a floating one that will hold the tablet,
The PH is very important you need to check it regular and the clorine, too much and it will burn the eyes, you should also have some shock it, iin case the water starts to turn .
Best thing is to go to your local pool shop and they will explain everything to you

Doug